| Value | Category | Cases | |
|---|---|---|---|
| 1993 | 1 |
0.4%
|
|
| 1995 | 1 |
0.4%
|
|
| 1996 | 1 |
0.4%
|
|
| 1997 | 12 |
4.9%
|
|
| 1998 | 231 |
93.9%
|
|
| Sysmiss | 25 |