| Value | Category | Cases | |
|---|---|---|---|
| 99 | Mising | 0 |
0%
|
| 1984 | 1 |
2.3%
|
|
| 1988 | 38 |
86.4%
|
|
| 1989 | 4 |
9.1%
|
|
| 1994 | 1 |
2.3%
|
|
| Sysmiss | 1681 |