| Value | Category | 
                                    
                    
                        | 1 | almost every day | 
                                    
                    
                        | 2 | once or twice a week | 
                                    
                    
                        | 3 | once or twice a month | 
                                    
                    
                        | 4 | never, or hardly ever | 
                                    
                    
                        | 6 | not appl. | 
                                    
                    
                        | 8 | not admin. | 
                                    
                    
                        | 9 | omitted | 
                                    
                    
                        | 11 | .B | 
                            
            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.