| Value | Category | Cases | |
|---|---|---|---|
| 1998 | 2 |
40%
|
|
| 1999 | 1 |
20%
|
|
| 2000 | 2 |
40%
|
|
| 9997 | inconsistent | 0 |
0%
|
| 9998 | dk | 0 |
0%
|
| Sysmiss | 6387 |