| Value | Category | Cases | |
|---|---|---|---|
| 1971 | 2 |
22.2%
|
|
| 1972 | 1 |
11.1%
|
|
| 1973 | 1 |
11.1%
|
|
| 1975 | 1 |
11.1%
|
|
| 1976 | 1 |
11.1%
|
|
| 1979 | 1 |
11.1%
|
|
| 1981 | 1 |
11.1%
|
|
| 1982 | 1 |
11.1%
|
|
| Sysmiss | 6746 |