| Value | Category | Cases | |
|---|---|---|---|
| 1949 | 24 |
7.9%
|
|
| 1950 | 30 |
9.8%
|
|
| 1960 | 46 |
15.1%
|
|
| 1970 | 45 |
14.8%
|
|
| 1980 | 57 |
18.7%
|
|
| 1990 | 45 |
14.8%
|
|
| 2000 | 56 |
18.4%
|
|
| 2010 | 2 |
0.7%
|
|
| Sysmiss | 1 |