| Value | 
                    Category | 
                                                                            
                                    
                    
                        | -95 | 
                          | 
                        
                            
                        
                        
                        
                        
                            
                    
                                    
                    
                        | -90 | 
                        Not specified by supervisor/interviewer  | 
                        
                            
                        
                        
                        
                        
                            
                    
                                    
                    
                        | 1993 | 
                          | 
                        
                            
                        
                        
                        
                        
                            
                    
                                    
                    
                        | 1995 | 
                          | 
                        
                            
                        
                        
                        
                        
                            
                    
                                    
                    
                        | 1997 | 
                          | 
                        
                            
                        
                        
                        
                        
                            
                    
                                    
                    
                        | 2006 | 
                          | 
                        
                            
                        
                        
                        
                        
                            
                    
                                    
                    
                        | 2007 | 
                          | 
                        
                            
                        
                        
                        
                        
                            
                    
                                    
                    
                        | 2010 | 
                          | 
                        
                            
                        
                        
                        
                        
                            
                    
                                    
                    
                        | 2012 | 
                          | 
                        
                            
                        
                        
                        
                        
                            
                    
                            
            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.