| Value | Category | 
                                    
                    
                        | 1 | yes, less then 10 minutes | 
                                    
                    
                        | 2 | yes, 10 minutes and more | 
                                    
                    
                        | 3 | no | 
                                    
                    
                        | 8 | don't know | 
                                    
                    
                        | Sysmiss |  | 
                            
            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.