| Value | Category | Cases | |
|---|---|---|---|
| 1990 | 1 | 
                                                                 
                                    
                                    0.3%
                                 
                                                             | 
                                                        
                    |
| 1991 | 1 | 
                                                                 
                                    
                                    0.3%
                                 
                                                             | 
                                                        
                    |
| 1992 | 1 | 
                                                                 
                                    
                                    0.3%
                                 
                                                             | 
                                                        
                    |
| 1994 | 5 | 
                                                                 
                                    
                                    1.4%
                                 
                                                             | 
                                                        
                    |
| 1995 | 7 | 
                                                                 
                                    
                                    1.9%
                                 
                                                             | 
                                                        
                    |
| 1996 | 112 | 
                                                                 
                                    
                                    30.3%
                                 
                                                             | 
                                                        
                    |
| 1997 | 110 | 
                                                                 
                                    
                                    29.7%
                                 
                                                             | 
                                                        
                    |
| 1998 | 130 | 
                                                                 
                                    
                                    35.1%
                                 
                                                             | 
                                                        
                    |
| 7777 | Don't Know | 3 | 
                                                                 
                                    
                                    0.8%
                                 
                                                             | 
                                                        
                    
| 9999 | Refused | 0 | 
                                                                 
                                    
                                    0%
                                 
                                                             | 
                                                        
                    
| Sysmiss | 4901 |