| Value | Category | Cases | |
|---|---|---|---|
| 99 | Mising | 0 |
0%
|
| 1984 | 1 |
4.3%
|
|
| 1988 | 18 |
78.3%
|
|
| 1989 | 2 |
8.7%
|
|
| 1990 | 1 |
4.3%
|
|
| 1993 | 1 |
4.3%
|
|
| Sysmiss | 1702 |