| Value | Category | 
                                    
                    
                        | -3 | Missing | 
                                    
                    
                        | 1 | Daily | 
                                    
                    
                        | 2 | Every 2nd day | 
                                    
                    
                        | 3 | Twice a week | 
                                    
                    
                        | 4 | Once a week | 
                                    
                    
                        | 5 | Less than once a week | 
                                    
                    
                        | 6 | Less than once a month | 
                            
            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.