| Value | Category | Cases | |
|---|---|---|---|
| 1967 | 2 |
18.2%
|
|
| 1973 | 1 |
9.1%
|
|
| 1977 | 1 |
9.1%
|
|
| 1980 | 3 |
27.3%
|
|
| 1982 | 3 |
27.3%
|
|
| 1986 | 1 |
9.1%
|
|
| Sysmiss | 420 |