| Value | Category | Cases | |
|---|---|---|---|
| 1975 | 2 |
0.8%
|
|
| 1983 | 2 |
0.8%
|
|
| 1990 | 2 |
0.8%
|
|
| 1997 | 6 |
2.3%
|
|
| 1999 | 2 |
0.8%
|
|
| 2000 | 11 |
4.3%
|
|
| 2002 | 6 |
2.3%
|
|
| 2003 | 2 |
0.8%
|
|
| 2005 | 6 |
2.3%
|
|
| 2006 | 10 |
3.9%
|
|
| 2007 | 29 |
11.2%
|
|
| 2008 | 31 |
12%
|
|
| 2009 | 36 |
14%
|
|
| 2010 | 36 |
14%
|
|
| 2011 | 40 |
15.5%
|
|
| 2012 | 16 |
6.2%
|
|
| 9998 | don't know | 21 |
8.1%
|
| Sysmiss | 48928 |