| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 5 |
14.3%
|
| 1985 | 1 |
2.9%
|
|
| 1990 | 1 |
2.9%
|
|
| 1992 | 1 |
2.9%
|
|
| 1998 | 1 |
2.9%
|
|
| 2000 | 6 |
17.1%
|
|
| 2002 | 2 |
5.7%
|
|
| 2003 | 1 |
2.9%
|
|
| 2005 | 1 |
2.9%
|
|
| 2006 | 1 |
2.9%
|
|
| 2008 | 1 |
2.9%
|
|
| 2009 | 2 |
5.7%
|
|
| 2011 | 1 |
2.9%
|
|
| 2013 | 3 |
8.6%
|
|
| 2015 | 1 |
2.9%
|
|
| 2016 | 1 |
2.9%
|
|
| 2017 | 1 |
2.9%
|
|
| 2019 | 1 |
2.9%
|
|
| 2020 | 2 |
5.7%
|
|
| 2021 | 2 |
5.7%
|
|
| Sysmiss | 367 |