| Value | Category | Cases | |
|---|---|---|---|
| 1990 | 23 |
82.1%
|
|
| 1991 | 1 |
3.6%
|
|
| 1993 | 1 |
3.6%
|
|
| 1995 | 2 |
7.1%
|
|
| 1997 | 1 |
3.6%
|
|
| Sysmiss | 893 |