| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 23 |
39.7%
|
| 1990 | 1 |
1.7%
|
|
| 1994 | 1 |
1.7%
|
|
| 1999 | 1 |
1.7%
|
|
| 2000 | 1 |
1.7%
|
|
| 2002 | 1 |
1.7%
|
|
| 2003 | 1 |
1.7%
|
|
| 2005 | 1 |
1.7%
|
|
| 2006 | 2 |
3.4%
|
|
| 2007 | 1 |
1.7%
|
|
| 2008 | 1 |
1.7%
|
|
| 2009 | 2 |
3.4%
|
|
| 2010 | 2 |
3.4%
|
|
| 2011 | 3 |
5.2%
|
|
| 2012 | 2 |
3.4%
|
|
| 2013 | 2 |
3.4%
|
|
| 2014 | 4 |
6.9%
|
|
| 2015 | 4 |
6.9%
|
|
| 2016 | 1 |
1.7%
|
|
| 2018 | 4 |
6.9%
|
|
| Sysmiss | 294 |