| Value | Category | Cases | |
|---|---|---|---|
| 1996 | 16 |
14.8%
|
|
| 1997 | 39 |
36.1%
|
|
| 1998 | 42 |
38.9%
|
|
| 1999 | 11 |
10.2%
|
|
| Sysmiss | 4317 |