| Value | Category | 
                                    
                    
                        | 95 | 95. Topcode | 
                                    
                    
                        | 96 | 96. N/A | 
                                    
                    
                        | 97 | 97. Refuse | 
                                    
                    
                        | 98 | 98. DK | 
                                    
                    
                        | 99 | 99. Miss | 
                                    
                    
                        | 1992 |  | 
                                    
                    
                        | 1993 |  | 
                                    
                    
                        | 1994 |  | 
                                    
                    
                        | 1995 |  | 
                                    
                    
                        | 1996 |  | 
                                    
                    
                        | 1997 |  | 
                                    
                    
                        | 1998 |  | 
                                    
                    
                        | Sysmiss |  | 
                            
            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.