| Value | Category | Cases | |
|---|---|---|---|
| 1995 | 12 |
0.7%
|
|
| 1996 | 127 |
7.4%
|
|
| 1997 | 164 |
9.6%
|
|
| 1998 | 297 |
17.3%
|
|
| 1999 | 541 |
31.5%
|
|
| 2000 | 576 |
33.5%
|
|
| 9997 | inconsistent | 0 |
0%
|
| 9998 | dk | 0 |
0%
|
| Sysmiss | 5038 |