| Value | Category | 
                                    
                    
                        | 1 | Yes, all the time | 
                                    
                    
                        | 2 | Yes, sometimes | 
                                    
                    
                        | 3 | No | 
                                    
                    
                        | 4 | Na (if not working or not attending schoool) | 
                                    
                    
                        | 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.