| Value | Category | Cases | |
|---|---|---|---|
| 1956 | 2 |
13.3%
|
|
| 1961 | 1 |
6.7%
|
|
| 1966 | 2 |
13.3%
|
|
| 1967 | 1 |
6.7%
|
|
| 1971 | 1 |
6.7%
|
|
| 1975 | 1 |
6.7%
|
|
| 1977 | 1 |
6.7%
|
|
| 1981 | 1 |
6.7%
|
|
| 1993 | 3 |
20%
|
|
| 1996 | 1 |
6.7%
|
|
| 1998 | 1 |
6.7%
|
|
| 9999 | 9999. Don't know | 0 |
0%
|
| Sysmiss | 984 |