Value | Category | Cases | |
---|---|---|---|
-9 | Don't know (spontaneous) | 0 |
0%
|
1857 | 1 |
0.2%
|
|
1860 | 1 |
0.2%
|
|
1868 | 1 |
0.2%
|
|
1888 | 1 |
0.2%
|
|
1904 | 1 |
0.2%
|
|
1910 | 1 |
0.2%
|
|
1919 | 1 |
0.2%
|
|
1935 | 1 |
0.2%
|
|
1936 | 3 |
0.6%
|
|
1939 | 2 |
0.4%
|
|
1941 | 1 |
0.2%
|
|
1943 | 3 |
0.6%
|
|
1945 | 1 |
0.2%
|
|
1948 | 2 |
0.4%
|
|
1951 | 1 |
0.2%
|
|
1952 | 7 |
1.3%
|
|
1953 | 2 |
0.4%
|
|
1955 | 1 |
0.2%
|
|
1956 | 2 |
0.4%
|
|
1957 | 2 |
0.4%
|
|
1958 | 1 |
0.2%
|
|
1960 | 7 |
1.3%
|
|
1961 | 2 |
0.4%
|
|
1962 | 1 |
0.2%
|
|
1964 | 5 |
0.9%
|
|
1965 | 2 |
0.4%
|
|
1966 | 3 |
0.6%
|
|
1967 | 2 |
0.4%
|
|
1968 | 2 |
0.4%
|
|
1969 | 1 |
0.2%
|
|
1970 | 10 |
1.9%
|
|
1971 | 2 |
0.4%
|
|
1972 | 4 |
0.8%
|
|
1973 | 2 |
0.4%
|
|
1974 | 3 |
0.6%
|
|
1975 | 7 |
1.3%
|
|
1976 | 5 |
0.9%
|
|
1977 | 5 |
0.9%
|
|
1978 | 7 |
1.3%
|
|
1979 | 4 |
0.8%
|
|
1980 | 18 |
3.4%
|
|
1981 | 7 |
1.3%
|
|
1982 | 16 |
3%
|
|
1983 | 5 |
0.9%
|
|
1984 | 5 |
0.9%
|
|
1985 | 13 |
2.4%
|
|
1986 | 5 |
0.9%
|
|
1987 | 10 |
1.9%
|
|
1988 | 6 |
1.1%
|
|
1989 | 5 |
0.9%
|
|
1990 | 22 |
4.1%
|
|
1991 | 7 |
1.3%
|
|
1992 | 20 |
3.8%
|
|
1993 | 12 |
2.3%
|
|
1994 | 18 |
3.4%
|
|
1995 | 19 |
3.6%
|
|
1996 | 10 |
1.9%
|
|
1997 | 15 |
2.8%
|
|
1998 | 9 |
1.7%
|
|
1999 | 13 |
2.4%
|
|
2000 | 24 |
4.5%
|
|
2001 | 6 |
1.1%
|
|
2002 | 16 |
3%
|
|
2003 | 14 |
2.6%
|
|
2004 | 13 |
2.4%
|
|
2005 | 11 |
2.1%
|
|
2006 | 13 |
2.4%
|
|
2007 | 16 |
3%
|
|
2008 | 11 |
2.1%
|
|
2009 | 12 |
2.3%
|
|
2010 | 11 |
2.1%
|
|
2011 | 14 |
2.6%
|
|
2012 | 2 |
0.4%
|
|
2013 | 6 |
1.1%
|
|
2014 | 5 |
0.9%
|
|
2015 | 5 |
0.9%
|
|
2016 | 3 |
0.6%
|
|
2017 | 3 |
0.6%
|
|
2018 | 2 |
0.4%
|