| Value | Category | Cases | |
|---|---|---|---|
| 1997 | 6 |
3.6%
|
|
| 1998 | 12 |
7.1%
|
|
| 1999 | 23 |
13.7%
|
|
| 2000 | 27 |
16.1%
|
|
| 2001 | 73 |
43.5%
|
|
| 2002 | 27 |
16.1%
|
|
| Sysmiss | 8 |