| Value | Category | 
                                    
                    
                        | 1 | 1. Daily | 
                                    
                    
                        | 2 | 2. At least once a week | 
                                    
                    
                        | 3 | 3. At least once a month | 
                                    
                    
                        | 4 | 4. At least once a year | 
                                    
                    
                        | 5 | 5. Less than once a year | 
                                    
                    
                        | 6 | 6. Don't know | 
                            
            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.