| Value | Category | Cases | |
|---|---|---|---|
| 1995 | 3 |
11.1%
|
|
| 1996 | 16 |
59.3%
|
|
| 1997 | 7 |
25.9%
|
|
| 1998 | 1 |
3.7%
|
|
| 9997 | inconsistent | 0 |
0%
|
| 9998 | dk | 0 |
0%
|
| Sysmiss | 6728 |