| Value | 
                    Category | 
                                                                            
                                    
                    
                        | 1 | 
                        a  | 
                        
                            
                        
                        
                        
                        
                            
                    
                                    
                    
                        | 2 | 
                        b  | 
                        
                            
                        
                        
                        
                        
                            
                    
                                    
                    
                        | 3 | 
                        c  | 
                        
                            
                        
                        
                        
                        
                            
                    
                                    
                    
                        | 4 | 
                        d  | 
                        
                            
                        
                        
                        
                        
                            
                    
                                    
                    
                        | 6 | 
                        not reached  | 
                        
                            
                        
                        
                        
                        
                            
                    
                                    
                    
                        | 7 | 
                        two or more responses, not interpretable  | 
                        
                            
                        
                        
                        
                        
                            
                    
                                    
                    
                        | 8 | 
                        not admin.  | 
                        
                            
                        
                        
                        
                        
                            
                    
                                    
                    
                        | 9 | 
                        missing (blank only)  | 
                        
                            
                        
                        
                        
                        
                            
                    
                                    
                    
                        | 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.