| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 46 |
7.6%
|
| 1873 | 1 |
0.2%
|
|
| 1881 | 1 |
0.2%
|
|
| 1930 | 3 |
0.5%
|
|
| 1955 | 1 |
0.2%
|
|
| 1958 | 1 |
0.2%
|
|
| 1960 | 10 |
1.7%
|
|
| 1961 | 1 |
0.2%
|
|
| 1963 | 1 |
0.2%
|
|
| 1965 | 1 |
0.2%
|
|
| 1967 | 1 |
0.2%
|
|
| 1968 | 1 |
0.2%
|
|
| 1969 | 1 |
0.2%
|
|
| 1970 | 5 |
0.8%
|
|
| 1971 | 2 |
0.3%
|
|
| 1974 | 2 |
0.3%
|
|
| 1975 | 3 |
0.5%
|
|
| 1976 | 1 |
0.2%
|
|
| 1977 | 2 |
0.3%
|
|
| 1979 | 1 |
0.2%
|
|
| 1980 | 3 |
0.5%
|
|
| 1981 | 1 |
0.2%
|
|
| 1982 | 1 |
0.2%
|
|
| 1983 | 2 |
0.3%
|
|
| 1984 | 1 |
0.2%
|
|
| 1985 | 2 |
0.3%
|
|
| 1986 | 3 |
0.5%
|
|
| 1987 | 1 |
0.2%
|
|
| 1989 | 7 |
1.2%
|
|
| 1990 | 23 |
3.8%
|
|
| 1991 | 37 |
6.1%
|
|
| 1992 | 25 |
4.1%
|
|
| 1993 | 15 |
2.5%
|
|
| 1994 | 18 |
3%
|
|
| 1995 | 28 |
4.6%
|
|
| 1996 | 22 |
3.6%
|
|
| 1997 | 17 |
2.8%
|
|
| 1998 | 18 |
3%
|
|
| 1999 | 17 |
2.8%
|
|
| 2000 | 32 |
5.3%
|
|
| 2001 | 15 |
2.5%
|
|
| 2002 | 6 |
1%
|
|
| 2003 | 32 |
5.3%
|
|
| 2004 | 28 |
4.6%
|
|
| 2005 | 23 |
3.8%
|
|
| 2006 | 12 |
2%
|
|
| 2007 | 20 |
3.3%
|
|
| 2008 | 15 |
2.5%
|
|
| 2009 | 14 |
2.3%
|
|
| 2010 | 14 |
2.3%
|
|
| 2011 | 13 |
2.1%
|
|
| 2012 | 16 |
2.6%
|
|
| 2013 | 8 |
1.3%
|
|
| 2014 | 12 |
2%
|
|
| 2015 | 5 |
0.8%
|
|
| 2016 | 8 |
1.3%
|
|
| 2017 | 3 |
0.5%
|
|
| 2018 | 4 |
0.7%
|
|
| Sysmiss | 349 |