| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know | 3 |
1.8%
|
| 2002 | 1 |
0.6%
|
|
| 2004 | 3 |
1.8%
|
|
| 2007 | 3 |
1.8%
|
|
| 2008 | 13 |
8%
|
|
| 2009 | 11 |
6.7%
|
|
| 2010 | 33 |
20.2%
|
|
| 2011 | 21 |
12.9%
|
|
| 2012 | 31 |
19%
|
|
| 2013 | 44 |
27%
|
|
| Sysmiss | 319 |