| Value | Category | Cases | |
|---|---|---|---|
| 1990 | 18 |
2.3%
|
|
| 1991 | 175 |
22%
|
|
| 1992 | 597 |
75%
|
|
| 1993 | 3 |
0.4%
|
|
| 1994 | 2 |
0.3%
|
|
| 1995 | 1 |
0.1%
|
|
| Sysmiss | 1874 |