| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 14 |
4.6%
|
| 1873 | 1 |
0.3%
|
|
| 1874 | 1 |
0.3%
|
|
| 1886 | 1 |
0.3%
|
|
| 1894 | 2 |
0.7%
|
|
| 1906 | 1 |
0.3%
|
|
| 1934 | 1 |
0.3%
|
|
| 1949 | 1 |
0.3%
|
|
| 1951 | 1 |
0.3%
|
|
| 1956 | 1 |
0.3%
|
|
| 1958 | 1 |
0.3%
|
|
| 1960 | 1 |
0.3%
|
|
| 1962 | 1 |
0.3%
|
|
| 1964 | 2 |
0.7%
|
|
| 1965 | 2 |
0.7%
|
|
| 1966 | 2 |
0.7%
|
|
| 1969 | 1 |
0.3%
|
|
| 1970 | 1 |
0.3%
|
|
| 1974 | 1 |
0.3%
|
|
| 1975 | 4 |
1.3%
|
|
| 1977 | 2 |
0.7%
|
|
| 1978 | 2 |
0.7%
|
|
| 1979 | 2 |
0.7%
|
|
| 1980 | 1 |
0.3%
|
|
| 1981 | 2 |
0.7%
|
|
| 1982 | 2 |
0.7%
|
|
| 1985 | 2 |
0.7%
|
|
| 1986 | 4 |
1.3%
|
|
| 1987 | 1 |
0.3%
|
|
| 1988 | 1 |
0.3%
|
|
| 1989 | 2 |
0.7%
|
|
| 1990 | 4 |
1.3%
|
|
| 1991 | 3 |
1%
|
|
| 1992 | 2 |
0.7%
|
|
| 1993 | 1 |
0.3%
|
|
| 1994 | 3 |
1%
|
|
| 1995 | 4 |
1.3%
|
|
| 1996 | 1 |
0.3%
|
|
| 1997 | 5 |
1.6%
|
|
| 1998 | 7 |
2.3%
|
|
| 1999 | 5 |
1.6%
|
|
| 2000 | 8 |
2.6%
|
|
| 2001 | 5 |
1.6%
|
|
| 2002 | 3 |
1%
|
|
| 2003 | 5 |
1.6%
|
|
| 2004 | 6 |
2%
|
|
| 2005 | 4 |
1.3%
|
|
| 2006 | 9 |
2.9%
|
|
| 2007 | 13 |
4.2%
|
|
| 2008 | 6 |
2%
|
|
| 2009 | 5 |
1.6%
|
|
| 2010 | 9 |
2.9%
|
|
| 2011 | 12 |
3.9%
|
|
| 2012 | 19 |
6.2%
|
|
| 2013 | 12 |
3.9%
|
|
| 2014 | 23 |
7.5%
|
|
| 2015 | 11 |
3.6%
|
|
| 2016 | 6 |
2%
|
|
| 2017 | 15 |
4.9%
|
|
| 2018 | 11 |
3.6%
|
|
| 2019 | 9 |
2.9%
|
|
| 2020 | 7 |
2.3%
|
|
| 2021 | 7 |
2.3%
|
|
| 2022 | 3 |
1%
|
|
| 2023 | 3 |
1%
|