Value | Category | Cases | |
---|---|---|---|
-9 | Don't know (spontaneous) | 0 |
0%
|
1957 | 2 |
1.7%
|
|
1959 | 1 |
0.8%
|
|
1960 | 3 |
2.5%
|
|
1964 | 1 |
0.8%
|
|
1967 | 1 |
0.8%
|
|
1970 | 1 |
0.8%
|
|
1973 | 1 |
0.8%
|
|
1975 | 4 |
3.3%
|
|
1976 | 1 |
0.8%
|
|
1977 | 1 |
0.8%
|
|
1978 | 2 |
1.7%
|
|
1979 | 1 |
0.8%
|
|
1980 | 5 |
4.2%
|
|
1981 | 2 |
1.7%
|
|
1982 | 2 |
1.7%
|
|
1983 | 3 |
2.5%
|
|
1984 | 1 |
0.8%
|
|
1985 | 2 |
1.7%
|
|
1986 | 1 |
0.8%
|
|
1987 | 1 |
0.8%
|
|
1988 | 1 |
0.8%
|
|
1989 | 4 |
3.3%
|
|
1990 | 3 |
2.5%
|
|
1991 | 2 |
1.7%
|
|
1992 | 1 |
0.8%
|
|
1993 | 1 |
0.8%
|
|
1994 | 3 |
2.5%
|
|
1995 | 3 |
2.5%
|
|
1996 | 4 |
3.3%
|
|
1997 | 4 |
3.3%
|
|
1998 | 2 |
1.7%
|
|
1999 | 6 |
5%
|
|
2000 | 4 |
3.3%
|
|
2001 | 1 |
0.8%
|
|
2002 | 4 |
3.3%
|
|
2003 | 2 |
1.7%
|
|
2004 | 7 |
5.8%
|
|
2005 | 4 |
3.3%
|
|
2006 | 4 |
3.3%
|
|
2007 | 3 |
2.5%
|
|
2009 | 4 |
3.3%
|
|
2010 | 3 |
2.5%
|
|
2011 | 1 |
0.8%
|
|
2012 | 5 |
4.2%
|
|
2013 | 5 |
4.2%
|
|
2014 | 2 |
1.7%
|
|
2015 | 1 |
0.8%
|