| Value | Category | Cases | |
|---|---|---|---|
| 1993 | 2 |
2.5%
|
|
| 1994 | 1 |
1.3%
|
|
| 1995 | 52 |
65%
|
|
| 1996 | 8 |
10%
|
|
| 1997 | 17 |
21.3%
|
|
| Sysmiss | 230 |