| Value | Category | Cases | |
|---|---|---|---|
| 1996 | 8 |
25.8%
|
|
| 1997 | 9 |
29%
|
|
| 1998 | 10 |
32.3%
|
|
| 1999 | 4 |
12.9%
|
|
| Sysmiss | 4394 |