| Value | Category | Cases | |
|---|---|---|---|
| 1997 | 2 |
0.1%
|
|
| 1998 | 35 |
1.7%
|
|
| 1999 | 132 |
6.2%
|
|
| 2000 | 311 |
14.7%
|
|
| 2001 | 467 |
22.1%
|
|
| 2002 | 767 |
36.3%
|
|
| 2003 | 401 |
19%
|
|
| Sysmiss | 3885 |