| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 6 |
15%
|
| 1990 | 1 |
2.5%
|
|
| 1993 | 1 |
2.5%
|
|
| 1995 | 1 |
2.5%
|
|
| 1998 | 2 |
5%
|
|
| 2000 | 2 |
5%
|
|
| 2002 | 1 |
2.5%
|
|
| 2003 | 1 |
2.5%
|
|
| 2005 | 2 |
5%
|
|
| 2007 | 1 |
2.5%
|
|
| 2008 | 1 |
2.5%
|
|
| 2009 | 4 |
10%
|
|
| 2012 | 2 |
5%
|
|
| 2013 | 2 |
5%
|
|
| 2014 | 1 |
2.5%
|
|
| 2015 | 2 |
5%
|
|
| 2017 | 4 |
10%
|
|
| 2018 | 1 |
2.5%
|
|
| 2019 | 2 |
5%
|
|
| 2020 | 3 |
7.5%
|
|
| Sysmiss | 362 |