| Value | Category | Cases | |
|---|---|---|---|
| 1978 | 1 |
1.9%
|
|
| 1980 | 1 |
1.9%
|
|
| 1987 | 1 |
1.9%
|
|
| 1990 | 1 |
1.9%
|
|
| 1991 | 1 |
1.9%
|
|
| 1992 | 1 |
1.9%
|
|
| 1993 | 3 |
5.6%
|
|
| 1994 | 6 |
11.1%
|
|
| 1995 | 5 |
9.3%
|
|
| 1996 | 14 |
25.9%
|
|
| 1997 | 20 |
37%
|
|
| Sysmiss | 249 |