| Value | 
                    Category | 
                                                                            
                                    
                    
                        | 00 | 
                        NIU (not in universe)  | 
                        
                            
                        
                        
                        
                        
                            
                    
                                    
                    
                        | 10 | 
                        None, does not travel to work or school  | 
                        
                            
                        
                        
                        
                        
                            
                    
                                    
                    
                        | 20 | 
                        Walking  | 
                        
                            
                        
                        
                        
                        
                            
                    
                                    
                    
                        | 21 | 
                        Walks or bicycle  | 
                        
                            
                        
                        
                        
                        
                            
                    
                                    
                    
                        | 22 | 
                        Walks, bicycle, or motorcycle  | 
                        
                            
                        
                        
                        
                        
                            
                    
                                    
                    
                        | 30 | 
                        Private vehicle  | 
                        
                            
                        
                        
                        
                        
                            
                    
                                    
                    
                        | 31 | 
                        Auto, truck, van  | 
                        
                            
                        
                        
                        
                        
                            
                    
                                    
                    
                        | 32 | 
                        Auto (driver)  | 
                        
                            
                        
                        
                        
                        
                            
                    
                                    
                    
                        | 33 | 
                        Auto (passenger)  | 
                        
                            
                        
                        
                        
                        
                            
                    
                                    
                    
                        | 34 | 
                        Auto, motorcycle, moped  | 
                        
                            
                        
                        
                        
                        
                            
                    
                                    
                    
                        | 35 | 
                        Motorcycle, moped, or scooter  | 
                        
                            
                        
                        
                        
                        
                            
                    
                                    
                    
                        | 36 | 
                        Bicycle  | 
                        
                            
                        
                        
                        
                        
                            
                    
                                    
                    
                        | 37 | 
                        Bicycle or motorcycle/moped  | 
                        
                            
                        
                        
                        
                        
                            
                    
                                    
                    
                        | 38 | 
                        Boat  | 
                        
                            
                        
                        
                        
                        
                            
                    
                                    
                    
                        | 40 | 
                        Public transportation  | 
                        
                            
                        
                        
                        
                        
                            
                    
                                    
                    
                        | 41 | 
                        Bus or trolley bus  | 
                        
                            
                        
                        
                        
                        
                            
                    
                                    
                    
                        | 42 | 
                        Bus or streetcar  | 
                        
                            
                        
                        
                        
                        
                            
                    
                                    
                    
                        | 43 | 
                        Streetcar or trolley car  | 
                        
                            
                        
                        
                        
                        
                            
                    
                                    
                    
                        | 44 | 
                        Railroad or train  | 
                        
                            
                        
                        
                        
                        
                            
                    
                                    
                    
                        | 45 | 
                        Subway or elevated train  | 
                        
                            
                        
                        
                        
                        
                            
                    
                                    
                    
                        | 46 | 
                        Other public transportation  | 
                        
                            
                        
                        
                        
                        
                            
                    
                                    
                    
                        | 50 | 
                        Other  | 
                        
                            
                        
                        
                        
                        
                            
                    
                                    
                    
                        | 51 | 
                        Taxicab  | 
                        
                            
                        
                        
                        
                        
                            
                    
                                    
                    
                        | 52 | 
                        Ferryboat  | 
                        
                            
                        
                        
                        
                        
                            
                    
                                    
                    
                        | 53 | 
                        Special transportation (company coach, school bus, etc.)  | 
                        
                            
                        
                        
                        
                        
                            
                    
                                    
                    
                        | 54 | 
                        Hired transport  | 
                        
                            
                        
                        
                        
                        
                            
                    
                                    
                    
                        | 55 | 
                        Shared private transport  | 
                        
                            
                        
                        
                        
                        
                            
                    
                                    
                    
                        | 56 | 
                        Horse or animal-drawn vehicle  | 
                        
                            
                        
                        
                        
                        
                            
                    
                                    
                    
                        | 57 | 
                        Other, not elsewhere classified  | 
                        
                            
                        
                        
                        
                        
                            
                    
                                    
                    
                        | 60 | 
                        Combination of several means  | 
                        
                            
                        
                        
                        
                        
                            
                    
                                    
                    
                        | 99 | 
                        Unknown/missing  | 
                        
                            
                        
                        
                        
                        
                            
                    
                            
            Warning: these figures indicate the number of cases found in the data file. They cannot be interpreted as summary statistics of the population of interest.