Value | Category | Cases | |
---|---|---|---|
-9 | Don't know (spontaneous) | 1 |
0.3%
|
1882 | 1 |
0.3%
|
|
1923 | 1 |
0.3%
|
|
1936 | 1 |
0.3%
|
|
1946 | 1 |
0.3%
|
|
1947 | 2 |
0.6%
|
|
1948 | 1 |
0.3%
|
|
1955 | 1 |
0.3%
|
|
1956 | 2 |
0.6%
|
|
1957 | 2 |
0.6%
|
|
1959 | 1 |
0.3%
|
|
1964 | 1 |
0.3%
|
|
1966 | 1 |
0.3%
|
|
1967 | 1 |
0.3%
|
|
1968 | 3 |
0.8%
|
|
1972 | 2 |
0.6%
|
|
1974 | 1 |
0.3%
|
|
1975 | 1 |
0.3%
|
|
1977 | 1 |
0.3%
|
|
1978 | 1 |
0.3%
|
|
1982 | 1 |
0.3%
|
|
1983 | 1 |
0.3%
|
|
1984 | 1 |
0.3%
|
|
1986 | 1 |
0.3%
|
|
1987 | 1 |
0.3%
|
|
1988 | 1 |
0.3%
|
|
1989 | 4 |
1.1%
|
|
1990 | 12 |
3.3%
|
|
1991 | 13 |
3.6%
|
|
1992 | 25 |
6.9%
|
|
1993 | 24 |
6.7%
|
|
1994 | 18 |
5%
|
|
1995 | 15 |
4.2%
|
|
1996 | 9 |
2.5%
|
|
1997 | 6 |
1.7%
|
|
1998 | 15 |
4.2%
|
|
1999 | 12 |
3.3%
|
|
2000 | 14 |
3.9%
|
|
2001 | 16 |
4.4%
|
|
2002 | 9 |
2.5%
|
|
2003 | 14 |
3.9%
|
|
2004 | 9 |
2.5%
|
|
2005 | 14 |
3.9%
|
|
2006 | 11 |
3.1%
|
|
2007 | 17 |
4.7%
|
|
2008 | 8 |
2.2%
|
|
2009 | 9 |
2.5%
|
|
2010 | 12 |
3.3%
|
|
2011 | 6 |
1.7%
|
|
2012 | 9 |
2.5%
|
|
2013 | 8 |
2.2%
|
|
2014 | 3 |
0.8%
|
|
2015 | 5 |
1.4%
|
|
2016 | 6 |
1.7%
|
|
2017 | 5 |
1.4%
|