| Value | Category | Cases | |
|---|---|---|---|
| 1997 | 4 |
7.3%
|
|
| 1998 | 9 |
16.4%
|
|
| 1999 | 7 |
12.7%
|
|
| 2000 | 18 |
32.7%
|
|
| 2001 | 11 |
20%
|
|
| 2002 | 6 |
10.9%
|
|
| Sysmiss | 7994 |