| Value | Category | Cases | |
|---|---|---|---|
| 1997 | 4 |
2.8%
|
|
| 1998 | 8 |
5.6%
|
|
| 1999 | 21 |
14.8%
|
|
| 2000 | 23 |
16.2%
|
|
| 2001 | 48 |
33.8%
|
|
| 2002 | 38 |
26.8%
|
|
| Sysmiss | 7907 |