| Value | Category | Cases | |
|---|---|---|---|
| 1996 | 100 |
28.7%
|
|
| 1997 | 117 |
33.5%
|
|
| 1998 | 92 |
26.4%
|
|
| 1999 | 26 |
7.4%
|
|
| 2000 | 13 |
3.7%
|
|
| 9997 | inconsistent | 1 |
0.3%
|
| 9998 | dk | 0 |
0%
|
| Sysmiss | 6406 |