| Value | Category | Cases | |
|---|---|---|---|
| 1989 | 1 |
0.6%
|
|
| 1990 | 1 |
0.6%
|
|
| 1992 | 7 |
4.3%
|
|
| 1993 | 13 |
8.1%
|
|
| 1994 | 17 |
10.6%
|
|
| 1995 | 28 |
17.4%
|
|
| 1996 | 48 |
29.8%
|
|
| 1997 | 43 |
26.7%
|
|
| 1998 | 3 |
1.9%
|
|
| Sysmiss | 123 |