| Value | Category | Cases | |
|---|---|---|---|
| 1996 | 9 |
9.7%
|
|
| 1997 | 12 |
12.9%
|
|
| 1998 | 17 |
18.3%
|
|
| 1999 | 22 |
23.7%
|
|
| 2000 | 33 |
35.5%
|
|
| 9997 | inconsistent | 0 |
0%
|
| 9998 | dk | 0 |
0%
|
| Sysmiss | 6299 |