| Value | Category | 
                                    
                    
                        | 1 | 1. Every day | 
                                    
                    
                        | 2 | 2. Several times a week | 
                                    
                    
                        | 3 | 3. Several times a month | 
                                    
                    
                        | 4 | 4. Several times a year | 
                                    
                    
                        | 5 | 5. Never | 
                                    
                    
                        | 98 | 98. Refused | 
                                    
                    
                        | 99 | 99. 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.