| Value | Category | Cases | |
|---|---|---|---|
| 1990 | 119 | 
                                    
                                    10.9%
                                 | |
| 1991 | 938 | 
                                    
                                    86%
                                 | |
| 1992 | 34 | 
                                    
                                    3.1%
                                 | |
| Sysmiss | 1579 |