| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 71 |
51.8%
|
| 1974 | 1 |
0.7%
|
|
| 1985 | 1 |
0.7%
|
|
| 1986 | 1 |
0.7%
|
|
| 1991 | 1 |
0.7%
|
|
| 2004 | 1 |
0.7%
|
|
| 2005 | 3 |
2.2%
|
|
| 2006 | 2 |
1.5%
|
|
| 2007 | 1 |
0.7%
|
|
| 2008 | 2 |
1.5%
|
|
| 2009 | 4 |
2.9%
|
|
| 2010 | 7 |
5.1%
|
|
| 2011 | 3 |
2.2%
|
|
| 2012 | 3 |
2.2%
|
|
| 2014 | 1 |
0.7%
|
|
| 2015 | 2 |
1.5%
|
|
| 2016 | 2 |
1.5%
|
|
| 2017 | 8 |
5.8%
|
|
| 2018 | 8 |
5.8%
|
|
| 2019 | 7 |
5.1%
|
|
| 2020 | 4 |
2.9%
|
|
| 2021 | 4 |
2.9%
|
|
| Sysmiss | 882 |