| Value | Category | Cases | |
|---|---|---|---|
| 1991 | 1 |
0.2%
|
|
| 1992 | 30 |
4.6%
|
|
| 1993 | 73 |
11.1%
|
|
| 1994 | 84 |
12.8%
|
|
| 1995 | 103 |
15.7%
|
|
| 1996 | 172 |
26.3%
|
|
| 1997 | 189 |
28.9%
|
|
| 1998 | 3 |
0.5%
|
|
| Sysmiss | 9701 |