| Value | Category | Cases | |
|---|---|---|---|
| 1988 | 1 |
1.6%
|
|
| 1991 | 2 |
3.3%
|
|
| 1992 | 6 |
9.8%
|
|
| 1993 | 19 |
31.1%
|
|
| 1994 | 6 |
9.8%
|
|
| 7777 | 27 |
44.3%
|
|
| Sysmiss | 9568 |