Value | Category | Cases | |
---|---|---|---|
-9 | Don't know (spontaneous) | 95 |
8.7%
|
1927 | 1 |
0.1%
|
|
1929 | 2 |
0.2%
|
|
1930 | 1 |
0.1%
|
|
1934 | 1 |
0.1%
|
|
1944 | 2 |
0.2%
|
|
1945 | 1 |
0.1%
|
|
1947 | 1 |
0.1%
|
|
1951 | 1 |
0.1%
|
|
1952 | 2 |
0.2%
|
|
1953 | 2 |
0.2%
|
|
1954 | 2 |
0.2%
|
|
1956 | 1 |
0.1%
|
|
1957 | 1 |
0.1%
|
|
1958 | 1 |
0.1%
|
|
1959 | 1 |
0.1%
|
|
1960 | 6 |
0.5%
|
|
1961 | 2 |
0.2%
|
|
1962 | 2 |
0.2%
|
|
1964 | 1 |
0.1%
|
|
1965 | 2 |
0.2%
|
|
1967 | 2 |
0.2%
|
|
1968 | 2 |
0.2%
|
|
1969 | 6 |
0.5%
|
|
1970 | 5 |
0.5%
|
|
1971 | 1 |
0.1%
|
|
1972 | 3 |
0.3%
|
|
1973 | 3 |
0.3%
|
|
1974 | 6 |
0.5%
|
|
1975 | 6 |
0.5%
|
|
1976 | 7 |
0.6%
|
|
1977 | 3 |
0.3%
|
|
1978 | 4 |
0.4%
|
|
1979 | 5 |
0.5%
|
|
1980 | 17 |
1.6%
|
|
1981 | 5 |
0.5%
|
|
1982 | 9 |
0.8%
|
|
1983 | 5 |
0.5%
|
|
1984 | 13 |
1.2%
|
|
1985 | 13 |
1.2%
|
|
1986 | 11 |
1%
|
|
1987 | 9 |
0.8%
|
|
1988 | 15 |
1.4%
|
|
1989 | 16 |
1.5%
|
|
1990 | 29 |
2.6%
|
|
1991 | 15 |
1.4%
|
|
1992 | 16 |
1.5%
|
|
1993 | 18 |
1.6%
|
|
1994 | 23 |
2.1%
|
|
1995 | 16 |
1.5%
|
|
1996 | 24 |
2.2%
|
|
1997 | 12 |
1.1%
|
|
1998 | 24 |
2.2%
|
|
1999 | 29 |
2.6%
|
|
2000 | 50 |
4.6%
|
|
2001 | 31 |
2.8%
|
|
2002 | 33 |
3%
|
|
2003 | 27 |
2.5%
|
|
2004 | 36 |
3.3%
|
|
2005 | 31 |
2.8%
|
|
2006 | 37 |
3.4%
|
|
2007 | 32 |
2.9%
|
|
2008 | 40 |
3.6%
|
|
2009 | 48 |
4.4%
|
|
2010 | 60 |
5.5%
|
|
2011 | 20 |
1.8%
|
|
2012 | 24 |
2.2%
|
|
2013 | 27 |
2.5%
|
|
2014 | 27 |
2.5%
|
|
2015 | 11 |
1%
|
|
2016 | 19 |
1.7%
|
|
2017 | 43 |
3.9%
|