| Value | Category | Cases | |
|---|---|---|---|
| 1992 | 1 |
2.5%
|
|
| 1993 | 1 |
2.5%
|
|
| 1996 | 1 |
2.5%
|
|
| 1997 | 37 |
92.5%
|
|
| Sysmiss | 881 |