Value | Category | Cases | |
---|---|---|---|
-9 | Don't know (spontaneous) | 0 |
0%
|
1893 | 1 |
0.1%
|
|
1907 | 1 |
0.1%
|
|
1926 | 2 |
0.3%
|
|
1936 | 2 |
0.3%
|
|
1942 | 1 |
0.1%
|
|
1947 | 1 |
0.1%
|
|
1951 | 1 |
0.1%
|
|
1954 | 1 |
0.1%
|
|
1955 | 1 |
0.1%
|
|
1960 | 2 |
0.3%
|
|
1962 | 1 |
0.1%
|
|
1964 | 2 |
0.3%
|
|
1965 | 1 |
0.1%
|
|
1966 | 2 |
0.3%
|
|
1967 | 3 |
0.4%
|
|
1968 | 2 |
0.3%
|
|
1971 | 2 |
0.3%
|
|
1974 | 3 |
0.4%
|
|
1975 | 3 |
0.4%
|
|
1976 | 1 |
0.1%
|
|
1977 | 2 |
0.3%
|
|
1979 | 1 |
0.1%
|
|
1987 | 2 |
0.3%
|
|
1988 | 2 |
0.3%
|
|
1989 | 8 |
1%
|
|
1990 | 14 |
1.8%
|
|
1991 | 26 |
3.4%
|
|
1992 | 34 |
4.4%
|
|
1993 | 19 |
2.5%
|
|
1994 | 28 |
3.6%
|
|
1995 | 21 |
2.7%
|
|
1996 | 28 |
3.6%
|
|
1997 | 26 |
3.4%
|
|
1998 | 24 |
3.1%
|
|
1999 | 26 |
3.4%
|
|
2000 | 18 |
2.3%
|
|
2001 | 22 |
2.8%
|
|
2002 | 31 |
4%
|
|
2003 | 27 |
3.5%
|
|
2004 | 31 |
4%
|
|
2005 | 24 |
3.1%
|
|
2006 | 19 |
2.5%
|
|
2007 | 27 |
3.5%
|
|
2008 | 91 |
11.8%
|
|
2009 | 42 |
5.4%
|
|
2010 | 40 |
5.2%
|
|
2011 | 17 |
2.2%
|
|
2012 | 15 |
1.9%
|
|
2013 | 32 |
4.1%
|
|
2014 | 10 |
1.3%
|
|
2015 | 14 |
1.8%
|
|
2016 | 14 |
1.8%
|
|
2017 | 4 |
0.5%
|