| Value | Category | Cases | |
|---|---|---|---|
| 777 | Don't Know | 0 |
0%
|
| 1988 | 1 |
1.3%
|
|
| 1991 | 1 |
1.3%
|
|
| 1994 | 4 |
5.3%
|
|
| 1995 | 10 |
13.3%
|
|
| 1996 | 24 |
32%
|
|
| 1997 | 26 |
34.7%
|
|
| 1998 | 7 |
9.3%
|
|
| 7777 | 2 |
2.7%
|
|
| Sysmiss | 8323 |