| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 0 |
0%
|
| 2003 | 1 |
0.7%
|
|
| 2006 | 1 |
0.7%
|
|
| 2007 | 1 |
0.7%
|
|
| 2008 | 2 |
1.5%
|
|
| 2009 | 5 |
3.7%
|
|
| 2010 | 6 |
4.4%
|
|
| 2011 | 5 |
3.7%
|
|
| 2012 | 8 |
5.9%
|
|
| 2013 | 17 |
12.6%
|
|
| 2014 | 13 |
9.6%
|
|
| 2015 | 23 |
17%
|
|
| 2016 | 11 |
8.1%
|
|
| 2017 | 24 |
17.8%
|
|
| 2018 | 11 |
8.1%
|
|
| 2019 | 7 |
5.2%
|