| Value | Category | Cases | |
|---|---|---|---|
| 1996 | 28 |
25%
|
|
| 1997 | 43 |
38.4%
|
|
| 1998 | 32 |
28.6%
|
|
| 1999 | 9 |
8%
|
|
| Sysmiss | 4313 |