| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 0 |
0%
|
| 1892 | 1 |
0.2%
|
|
| 1894 | 1 |
0.2%
|
|
| 1906 | 1 |
0.2%
|
|
| 1911 | 1 |
0.2%
|
|
| 1920 | 1 |
0.2%
|
|
| 1921 | 1 |
0.2%
|
|
| 1927 | 1 |
0.2%
|
|
| 1930 | 1 |
0.2%
|
|
| 1943 | 1 |
0.2%
|
|
| 1945 | 1 |
0.2%
|
|
| 1947 | 2 |
0.5%
|
|
| 1948 | 1 |
0.2%
|
|
| 1949 | 1 |
0.2%
|
|
| 1951 | 1 |
0.2%
|
|
| 1953 | 3 |
0.7%
|
|
| 1954 | 2 |
0.5%
|
|
| 1955 | 3 |
0.7%
|
|
| 1957 | 1 |
0.2%
|
|
| 1958 | 1 |
0.2%
|
|
| 1960 | 2 |
0.5%
|
|
| 1965 | 2 |
0.5%
|
|
| 1968 | 2 |
0.5%
|
|
| 1970 | 2 |
0.5%
|
|
| 1971 | 1 |
0.2%
|
|
| 1972 | 1 |
0.2%
|
|
| 1974 | 1 |
0.2%
|
|
| 1976 | 2 |
0.5%
|
|
| 1977 | 1 |
0.2%
|
|
| 1978 | 1 |
0.2%
|
|
| 1980 | 1 |
0.2%
|
|
| 1982 | 1 |
0.2%
|
|
| 1984 | 1 |
0.2%
|
|
| 1988 | 4 |
1%
|
|
| 1989 | 2 |
0.5%
|
|
| 1990 | 36 |
8.9%
|
|
| 1991 | 27 |
6.7%
|
|
| 1992 | 28 |
6.9%
|
|
| 1993 | 21 |
5.2%
|
|
| 1994 | 35 |
8.7%
|
|
| 1995 | 16 |
4%
|
|
| 1996 | 22 |
5.4%
|
|
| 1997 | 16 |
4%
|
|
| 1998 | 13 |
3.2%
|
|
| 1999 | 10 |
2.5%
|
|
| 2000 | 11 |
2.7%
|
|
| 2001 | 8 |
2%
|
|
| 2002 | 10 |
2.5%
|
|
| 2003 | 7 |
1.7%
|
|
| 2004 | 3 |
0.7%
|
|
| 2005 | 3 |
0.7%
|
|
| 2006 | 5 |
1.2%
|
|
| 2007 | 8 |
2%
|
|
| 2008 | 4 |
1%
|
|
| 2009 | 9 |
2.2%
|
|
| 2010 | 12 |
3%
|
|
| 2011 | 14 |
3.5%
|
|
| 2012 | 10 |
2.5%
|
|
| 2013 | 13 |
3.2%
|
|
| 2014 | 9 |
2.2%
|
|
| 2015 | 4 |
1%
|
|
| 2016 | 1 |
0.2%
|