| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 36 |
22.6%
|
| 1955 | 1 |
0.6%
|
|
| 1970 | 1 |
0.6%
|
|
| 1991 | 3 |
1.9%
|
|
| 1993 | 1 |
0.6%
|
|
| 1995 | 1 |
0.6%
|
|
| 1996 | 2 |
1.3%
|
|
| 1997 | 1 |
0.6%
|
|
| 1998 | 5 |
3.1%
|
|
| 2000 | 4 |
2.5%
|
|
| 2001 | 2 |
1.3%
|
|
| 2002 | 2 |
1.3%
|
|
| 2003 | 1 |
0.6%
|
|
| 2004 | 2 |
1.3%
|
|
| 2005 | 2 |
1.3%
|
|
| 2007 | 4 |
2.5%
|
|
| 2008 | 4 |
2.5%
|
|
| 2009 | 6 |
3.8%
|
|
| 2010 | 11 |
6.9%
|
|
| 2011 | 2 |
1.3%
|
|
| 2012 | 3 |
1.9%
|
|
| 2013 | 5 |
3.1%
|
|
| 2014 | 7 |
4.4%
|
|
| 2015 | 11 |
6.9%
|
|
| 2016 | 14 |
8.8%
|
|
| 2017 | 16 |
10.1%
|
|
| 2018 | 12 |
7.5%
|
|
| Sysmiss | 1287 |