| Value | Category | Cases | |
|---|---|---|---|
| 1995 | 9 |
1.4%
|
|
| 1996 | 49 |
7.6%
|
|
| 1997 | 63 |
9.7%
|
|
| 1998 | 103 |
15.9%
|
|
| 1999 | 142 |
21.9%
|
|
| 2000 | 58 |
8.9%
|
|
| 9997 | Missing | 225 |
34.7%
|
| Sysmiss | 2055 |