| Value | Category | Cases | |
|---|---|---|---|
| 1995 | 12 |
0.7%
|
|
| 1996 | 123 |
7.1%
|
|
| 1997 | 168 |
9.7%
|
|
| 1998 | 297 |
17.2%
|
|
| 1999 | 546 |
31.6%
|
|
| 2000 | 581 |
33.6%
|
|
| 9997 | inconsistent | 0 |
0%
|
| 9998 | dk | 0 |
0%
|
| Sysmiss | 5028 |