| Value | Category | Cases | |
|---|---|---|---|
| 777 | Don't Know | 0 |
0%
|
| 1991 | 4 |
5.7%
|
|
| 1992 | 21 |
30%
|
|
| 1993 | 18 |
25.7%
|
|
| 1994 | 26 |
37.1%
|
|
| 7777 | 1 |
1.4%
|
|
| Sysmiss | 5511 |