| Value | Category | Cases | |
|---|---|---|---|
| 1997 | 1 |
1.5%
|
|
| 1998 | 3 |
4.6%
|
|
| 1999 | 7 |
10.8%
|
|
| 2000 | 12 |
18.5%
|
|
| 2001 | 27 |
41.5%
|
|
| 2002 | 15 |
23.1%
|
|
| Sysmiss | 7984 |