| Value | Category | 
                                    
                    
                        | 0 | Not at all | 
                                    
                    
                        | 1 | Less than once a week | 
                                    
                    
                        | 2 | At least once a week | 
                                    
                    
                        | 3 | Almost every day | 
                                    
                    
                        | 9 |  | 
                            
            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.