| Value | Category | 
                                    
                    
                        | 1980 |  | 
                                    
                    
                        | 1983 |  | 
                                    
                    
                        | 1985 |  | 
                                    
                    
                        | 1986 |  | 
                                    
                    
                        | 1988 |  | 
                                    
                    
                        | 1989 |  | 
                                    
                    
                        | 1990 |  | 
                                    
                    
                        | 1991 |  | 
                                    
                    
                        | 1992 |  | 
                                    
                    
                        | 1993 |  | 
                                    
                    
                        | 1994 |  | 
                                    
                    
                        | 1995 |  | 
                                    
                    
                        | 1996 |  | 
                                    
                    
                        | 1997 |  | 
                                    
                    
                        | 1998 |  | 
                                    
                    
                        | 1999 |  | 
                                    
                    
                        | 2000 |  | 
                                    
                    
                        | 2001 |  | 
                                    
                    
                        | 2002 |  | 
                                    
                    
                        | 5555 | ***Undefined Label | 
                                    
                    
                        | 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.