Value | Category | Cases | |
---|---|---|---|
-9 | Don't know (spontaneous) | 4 |
0.5%
|
1825 | 1 |
0.1%
|
|
1878 | 1 |
0.1%
|
|
1880 | 1 |
0.1%
|
|
1890 | 1 |
0.1%
|
|
1891 | 1 |
0.1%
|
|
1896 | 1 |
0.1%
|
|
1898 | 1 |
0.1%
|
|
1900 | 2 |
0.3%
|
|
1901 | 1 |
0.1%
|
|
1911 | 2 |
0.3%
|
|
1914 | 1 |
0.1%
|
|
1915 | 1 |
0.1%
|
|
1917 | 1 |
0.1%
|
|
1920 | 1 |
0.1%
|
|
1923 | 1 |
0.1%
|
|
1925 | 2 |
0.3%
|
|
1926 | 1 |
0.1%
|
|
1929 | 1 |
0.1%
|
|
1930 | 2 |
0.3%
|
|
1932 | 2 |
0.3%
|
|
1933 | 2 |
0.3%
|
|
1934 | 1 |
0.1%
|
|
1935 | 2 |
0.3%
|
|
1936 | 1 |
0.1%
|
|
1938 | 2 |
0.3%
|
|
1939 | 1 |
0.1%
|
|
1940 | 1 |
0.1%
|
|
1946 | 2 |
0.3%
|
|
1947 | 2 |
0.3%
|
|
1948 | 1 |
0.1%
|
|
1949 | 1 |
0.1%
|
|
1950 | 8 |
1.1%
|
|
1951 | 2 |
0.3%
|
|
1952 | 4 |
0.5%
|
|
1953 | 1 |
0.1%
|
|
1954 | 1 |
0.1%
|
|
1955 | 3 |
0.4%
|
|
1956 | 3 |
0.4%
|
|
1958 | 1 |
0.1%
|
|
1959 | 2 |
0.3%
|
|
1960 | 8 |
1.1%
|
|
1961 | 2 |
0.3%
|
|
1962 | 3 |
0.4%
|
|
1963 | 2 |
0.3%
|
|
1964 | 5 |
0.7%
|
|
1965 | 4 |
0.5%
|
|
1966 | 5 |
0.7%
|
|
1967 | 4 |
0.5%
|
|
1968 | 13 |
1.7%
|
|
1969 | 11 |
1.4%
|
|
1970 | 17 |
2.2%
|
|
1971 | 8 |
1.1%
|
|
1972 | 2 |
0.3%
|
|
1973 | 6 |
0.8%
|
|
1974 | 5 |
0.7%
|
|
1975 | 9 |
1.2%
|
|
1976 | 6 |
0.8%
|
|
1977 | 11 |
1.4%
|
|
1978 | 10 |
1.3%
|
|
1979 | 8 |
1.1%
|
|
1980 | 34 |
4.5%
|
|
1981 | 7 |
0.9%
|
|
1982 | 6 |
0.8%
|
|
1983 | 8 |
1.1%
|
|
1984 | 7 |
0.9%
|
|
1985 | 14 |
1.8%
|
|
1986 | 5 |
0.7%
|
|
1987 | 6 |
0.8%
|
|
1988 | 11 |
1.4%
|
|
1989 | 16 |
2.1%
|
|
1990 | 22 |
2.9%
|
|
1991 | 7 |
0.9%
|
|
1992 | 10 |
1.3%
|
|
1993 | 7 |
0.9%
|
|
1994 | 21 |
2.8%
|
|
1995 | 8 |
1.1%
|
|
1996 | 12 |
1.6%
|
|
1997 | 13 |
1.7%
|
|
1998 | 12 |
1.6%
|
|
1999 | 17 |
2.2%
|
|
2000 | 35 |
4.6%
|
|
2001 | 7 |
0.9%
|
|
2002 | 6 |
0.8%
|
|
2003 | 11 |
1.4%
|
|
2004 | 18 |
2.4%
|
|
2005 | 16 |
2.1%
|
|
2006 | 18 |
2.4%
|
|
2007 | 26 |
3.4%
|
|
2008 | 22 |
2.9%
|
|
2009 | 11 |
1.4%
|
|
2010 | 26 |
3.4%
|
|
2011 | 14 |
1.8%
|
|
2012 | 17 |
2.2%
|
|
2013 | 20 |
2.6%
|
|
2014 | 14 |
1.8%
|
|
2015 | 17 |
2.2%
|
|
2016 | 19 |
2.5%
|
|
2017 | 11 |
1.4%
|
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