| Value | Category | Cases | |
|---|---|---|---|
| 1972 | 22 |
11.5%
|
|
| 1976 | 69 |
35.9%
|
|
| 1979 | 55 |
28.6%
|
|
| 1984 | 1 |
0.5%
|
|
| 1986 | 1 |
0.5%
|
|
| 1988 | 44 |
22.9%
|
|
| Sysmiss | 6413 |