| Value | Category | Cases | |
|---|---|---|---|
| 1996 | 2 |
8.7%
|
|
| 1997 | 7 |
30.4%
|
|
| 1998 | 9 |
39.1%
|
|
| 1999 | 5 |
21.7%
|
|
| Sysmiss | 4402 |