| Value | Category | Cases | |
|---|---|---|---|
| 1995 | 12 |
1.7%
|
|
| 1996 | 63 |
9.1%
|
|
| 1997 | 81 |
11.6%
|
|
| 1998 | 122 |
17.5%
|
|
| 1999 | 182 |
26.1%
|
|
| 2000 | 78 |
11.2%
|
|
| 9997 | Missing | 158 |
22.7%
|
| Sysmiss | 2008 |