| Value | Category | Cases | |
|---|---|---|---|
| 1979 | 2 |
2.3%
|
|
| 1980 | 7 |
8%
|
|
| 1981 | 12 |
13.8%
|
|
| 1982 | 14 |
16.1%
|
|
| 1983 | 12 |
13.8%
|
|
| 1984 | 13 |
14.9%
|
|
| 1985 | 8 |
9.2%
|
|
| 1986 | 7 |
8%
|
|
| 1987 | 7 |
8%
|
|
| 1988 | 5 |
5.7%
|
|
| Sysmiss | 12 |