| Value | Category | Cases | |
|---|---|---|---|
| 1996 | 2 |
7.7%
|
|
| 1997 | 1 |
3.8%
|
|
| 1999 | 14 |
53.8%
|
|
| 2000 | 9 |
34.6%
|
|
| 9997 | inconsistent | 0 |
0%
|
| 9998 | dk | 0 |
0%
|
| Sysmiss | 15959 |