| Value | Category | 
                                    
                    
                        | 1 | Ususally always | 
                                    
                    
                        | 2 | Several hours per day | 
                                    
                    
                        | 3 | Once or twice a week | 
                                    
                    
                        | 4 | Infrequently | 
                            
            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.