Value | Category | Cases | |
---|---|---|---|
-9 | Don't know (spontaneous) | 0 |
0%
|
1882 | 1 |
0.3%
|
|
1896 | 2 |
0.6%
|
|
1926 | 1 |
0.3%
|
|
1947 | 2 |
0.6%
|
|
1948 | 1 |
0.3%
|
|
1953 | 1 |
0.3%
|
|
1954 | 1 |
0.3%
|
|
1955 | 1 |
0.3%
|
|
1961 | 1 |
0.3%
|
|
1972 | 2 |
0.6%
|
|
1978 | 1 |
0.3%
|
|
1984 | 2 |
0.6%
|
|
1985 | 1 |
0.3%
|
|
1986 | 1 |
0.3%
|
|
1987 | 1 |
0.3%
|
|
1988 | 1 |
0.3%
|
|
1989 | 5 |
1.4%
|
|
1990 | 8 |
2.2%
|
|
1991 | 5 |
1.4%
|
|
1992 | 6 |
1.7%
|
|
1993 | 8 |
2.2%
|
|
1994 | 8 |
2.2%
|
|
1995 | 16 |
4.4%
|
|
1996 | 22 |
6.1%
|
|
1997 | 24 |
6.7%
|
|
1998 | 8 |
2.2%
|
|
1999 | 12 |
3.3%
|
|
2000 | 26 |
7.2%
|
|
2001 | 25 |
6.9%
|
|
2002 | 17 |
4.7%
|
|
2003 | 10 |
2.8%
|
|
2004 | 15 |
4.2%
|
|
2005 | 15 |
4.2%
|
|
2006 | 8 |
2.2%
|
|
2007 | 12 |
3.3%
|
|
2008 | 9 |
2.5%
|
|
2009 | 5 |
1.4%
|
|
2010 | 6 |
1.7%
|
|
2011 | 7 |
1.9%
|
|
2012 | 9 |
2.5%
|
|
2013 | 9 |
2.5%
|
|
2014 | 7 |
1.9%
|
|
2015 | 12 |
3.3%
|
|
2016 | 9 |
2.5%
|
|
2017 | 6 |
1.7%
|
|
2018 | 3 |
0.8%
|
|
2019 | 4 |
1.1%
|
|
2020 | 3 |
0.8%
|
|
2021 | 1 |
0.3%
|