| Value | Category | Cases | |
|---|---|---|---|
| 1995 | 21 |
3.2%
|
|
| 1996 | 55 |
8.5%
|
|
| 1997 | 79 |
12.2%
|
|
| 1998 | 105 |
16.2%
|
|
| 1999 | 176 |
27.2%
|
|
| 2000 | 61 |
9.4%
|
|
| 9997 | Missing | 151 |
23.3%
|
| Sysmiss | 2056 |