| Value | 
                    Category | 
                                                                            
                                    
                    
                        | -99 | 
                        Don't know  | 
                        
                            
                        
                        
                        
                        
                            
                    
                                    
                    
                        | -97 | 
                        Not specified by supervisor/interviewer  | 
                        
                            
                        
                        
                        
                        
                            
                    
                                    
                    
                        | -95 | 
                          | 
                        
                            
                        
                        
                        
                        
                            
                    
                                    
                    
                        | 1992 | 
                          | 
                        
                            
                        
                        
                        
                        
                            
                    
                                    
                    
                        | 1994 | 
                          | 
                        
                            
                        
                        
                        
                        
                            
                    
                                    
                    
                        | 2000 | 
                          | 
                        
                            
                        
                        
                        
                        
                            
                    
                                    
                    
                        | 2004 | 
                          | 
                        
                            
                        
                        
                        
                        
                            
                    
                                    
                    
                        | 2007 | 
                          | 
                        
                            
                        
                        
                        
                        
                            
                    
                                    
                    
                        | 2010 | 
                          | 
                        
                            
                        
                        
                        
                        
                            
                    
                            
            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.