| Value | Category | Cases | |
|---|---|---|---|
| 1949 | 9 |
6.1%
|
|
| 1950 | 11 |
7.4%
|
|
| 1960 | 8 |
5.4%
|
|
| 1970 | 26 |
17.6%
|
|
| 1980 | 7 |
4.7%
|
|
| 1990 | 32 |
21.6%
|
|
| 2000 | 44 |
29.7%
|
|
| 2010 | 11 |
7.4%
|
|
| Sysmiss | 55 |