| Value | Category | Cases | |
|---|---|---|---|
| 1970 | 1 |
2.3%
|
|
| 1971 | 2 |
4.5%
|
|
| 1973 | 1 |
2.3%
|
|
| 1974 | 2 |
4.5%
|
|
| 1975 | 1 |
2.3%
|
|
| 1976 | 5 |
11.4%
|
|
| 1977 | 1 |
2.3%
|
|
| 1978 | 6 |
13.6%
|
|
| 1979 | 7 |
15.9%
|
|
| 1980 | 7 |
15.9%
|
|
| 1981 | 3 |
6.8%
|
|
| 1982 | 3 |
6.8%
|
|
| 1983 | 2 |
4.5%
|
|
| 1985 | 2 |
4.5%
|
|
| 1986 | 1 |
2.3%
|
|
| Sysmiss | 761 |