| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 18 |
10.3%
|
| 1989 | 1 |
0.6%
|
|
| 1999 | 1 |
0.6%
|
|
| 2000 | 2 |
1.1%
|
|
| 2005 | 1 |
0.6%
|
|
| 2006 | 1 |
0.6%
|
|
| 2010 | 4 |
2.3%
|
|
| 2012 | 1 |
0.6%
|
|
| 2013 | 2 |
1.1%
|
|
| 2014 | 4 |
2.3%
|
|
| 2015 | 15 |
8.6%
|
|
| 2016 | 29 |
16.7%
|
|
| 2017 | 40 |
23%
|
|
| 2018 | 55 |
31.6%
|
|
| Sysmiss | 586 |