| Value | Category | Cases | |
|---|---|---|---|
| 1998 | 4 |
33.3%
|
|
| 2000 | 3 |
25%
|
|
| 2001 | 3 |
25%
|
|
| 2002 | 2 |
16.7%
|
|
| Sysmiss | 138 |