| Value | Category | Cases | |
|---|---|---|---|
| 1949 | 19 |
4.8%
|
|
| 1950 | 34 |
8.5%
|
|
| 1960 | 37 |
9.3%
|
|
| 1970 | 149 |
37.4%
|
|
| 1980 | 22 |
5.5%
|
|
| 1990 | 31 |
7.8%
|
|
| 2000 | 98 |
24.6%
|
|
| 2010 | 8 |
2%
|
|
| Sysmiss | 2 |