| Value | Category | Cases | |
|---|---|---|---|
| 1997 | 3 |
27.3%
|
|
| 1998 | 4 |
36.4%
|
|
| 1999 | 2 |
18.2%
|
|
| 2000 | 2 |
18.2%
|
|
| 9997 | inconsistent | 0 |
0%
|
| 9998 | dk | 0 |
0%
|
| Sysmiss | 6381 |