| Value | Category | Cases | |
|---|---|---|---|
| 1949 | 13 |
6.6%
|
|
| 1950 | 12 |
6.1%
|
|
| 1960 | 14 |
7.1%
|
|
| 1970 | 33 |
16.8%
|
|
| 1980 | 18 |
9.2%
|
|
| 1990 | 53 |
27%
|
|
| 2000 | 46 |
23.5%
|
|
| 2010 | 7 |
3.6%
|
|
| Sysmiss | 4 |