| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 19 |
8.8%
|
| 1943 | 1 |
0.5%
|
|
| 1973 | 2 |
0.9%
|
|
| 1979 | 1 |
0.5%
|
|
| 1980 | 1 |
0.5%
|
|
| 1983 | 1 |
0.5%
|
|
| 1991 | 1 |
0.5%
|
|
| 1992 | 1 |
0.5%
|
|
| 1994 | 2 |
0.9%
|
|
| 1995 | 1 |
0.5%
|
|
| 1996 | 1 |
0.5%
|
|
| 1998 | 3 |
1.4%
|
|
| 2000 | 2 |
0.9%
|
|
| 2001 | 1 |
0.5%
|
|
| 2002 | 4 |
1.8%
|
|
| 2003 | 2 |
0.9%
|
|
| 2004 | 3 |
1.4%
|
|
| 2005 | 2 |
0.9%
|
|
| 2006 | 6 |
2.8%
|
|
| 2007 | 1 |
0.5%
|
|
| 2008 | 3 |
1.4%
|
|
| 2009 | 8 |
3.7%
|
|
| 2010 | 13 |
6%
|
|
| 2011 | 6 |
2.8%
|
|
| 2012 | 4 |
1.8%
|
|
| 2013 | 12 |
5.5%
|
|
| 2014 | 17 |
7.8%
|
|
| 2015 | 23 |
10.6%
|
|
| 2016 | 22 |
10.1%
|
|
| 2017 | 25 |
11.5%
|
|
| 2018 | 29 |
13.4%
|
|
| Sysmiss | 1022 |