| Value | Category | Cases | |
|---|---|---|---|
| 1990 | 26 |
65%
|
|
| 1991 | 3 |
7.5%
|
|
| 1992 | 1 |
2.5%
|
|
| 1993 | 4 |
10%
|
|
| 1995 | 3 |
7.5%
|
|
| 1996 | 2 |
5%
|
|
| 1997 | 1 |
2.5%
|
|
| Sysmiss | 881 |