| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 10 |
15.2%
|
| 1976 | 1 |
1.5%
|
|
| 1981 | 1 |
1.5%
|
|
| 1984 | 1 |
1.5%
|
|
| 1987 | 2 |
3%
|
|
| 1992 | 2 |
3%
|
|
| 1993 | 1 |
1.5%
|
|
| 1998 | 1 |
1.5%
|
|
| 2000 | 3 |
4.5%
|
|
| 2001 | 1 |
1.5%
|
|
| 2002 | 1 |
1.5%
|
|
| 2003 | 1 |
1.5%
|
|
| 2004 | 1 |
1.5%
|
|
| 2005 | 2 |
3%
|
|
| 2006 | 2 |
3%
|
|
| 2008 | 1 |
1.5%
|
|
| 2010 | 2 |
3%
|
|
| 2011 | 2 |
3%
|
|
| 2012 | 2 |
3%
|
|
| 2013 | 2 |
3%
|
|
| 2014 | 5 |
7.6%
|
|
| 2015 | 3 |
4.5%
|
|
| 2016 | 1 |
1.5%
|
|
| 2017 | 4 |
6.1%
|
|
| 2018 | 1 |
1.5%
|
|
| 2019 | 3 |
4.5%
|
|
| 2020 | 2 |
3%
|
|
| 2021 | 2 |
3%
|
|
| 2022 | 4 |
6.1%
|
|
| 2023 | 2 |
3%
|
|
| Sysmiss | 556 |