| Value | Category | Cases | |
|---|---|---|---|
| 1997 | 6 |
4.9%
|
|
| 1998 | 55 |
44.7%
|
|
| 1999 | 35 |
28.5%
|
|
| 2000 | 27 |
22%
|
|
| Sysmiss | 8873 |