| Value | Category | Cases | |
|---|---|---|---|
| 1991 | 1 |
0.2%
|
|
| 1992 | 18 |
3.2%
|
|
| 1993 | 64 |
11.5%
|
|
| 1994 | 83 |
14.9%
|
|
| 1995 | 79 |
14.2%
|
|
| 1996 | 145 |
26.1%
|
|
| 1997 | 162 |
29.1%
|
|
| 1998 | 4 |
0.7%
|
|
| Sysmiss | 9800 |