| Value | Category | Cases | |
|---|---|---|---|
| 1979 | 1 |
3.2%
|
|
| 1980 | 1 |
3.2%
|
|
| 1981 | 3 |
9.7%
|
|
| 1982 | 11 |
35.5%
|
|
| 1983 | 12 |
38.7%
|
|
| 1984 | 2 |
6.5%
|
|
| 1989 | 1 |
3.2%
|