| Value | Category | Cases | |
|---|---|---|---|
| 1995 | 10 |
1.6%
|
|
| 1996 | 40 |
6.5%
|
|
| 1997 | 60 |
9.7%
|
|
| 1998 | 80 |
12.9%
|
|
| 1999 | 112 |
18.1%
|
|
| 2000 | 53 |
8.6%
|
|
| 9997 | Missing | 264 |
42.6%
|
| Sysmiss | 2085 |