| Value | Category | Cases | |
|---|---|---|---|
| 1999 | 17 |
19.3%
|
|
| 2000 | 37 |
42%
|
|
| 2001 | 28 |
31.8%
|
|
| 2002 | 6 |
6.8%
|
|
| Sysmiss | 4555 |