| Year | Count |
|---|---|
| 1969 | 21 |
| 1970 | 10 |
| 1971 | 12 |
| 1972 | 10 |
| 1973 | 25 |
| 1974 | 6 |
| 1975 | 7 |
| 1976 | 19 |
| 1977 | 21 |
| 1978 | 12 |
| 1979 | 11 |
| 1980 | 5 |
| 1981 | 12 |
| 1982 | 15 |
| 1983 | 15 |
| 1984 | 10 |
| 1985 | 10 |
| 1986 | 7 |
| 1987 | 20 |
| 1988 | 53 |
| 1989 | 73 |
| 1990 | 56 |
| 1991 | 35 |
| 1992 | 67 |
| 1993 | 52 |
| 1994 | 42 |
| 1995 | 35 |
| 1996 | 24 |
| 1997 | 200 |
| 1998 | 149 |
| 1999 | 100 |
| 2000 | 65 |
| 2001 | 119 |
| 2002 | 103 |
| 2003 | 99 |
| 2004 | 159 |
| 2005 | 202 |
| 2006 | 103 |
| 2007 | 103 |
| 2008 | 137 |
| 2009 | 55 |
| 2010 | 55 |
| 2011 | 42 |
| 2012 | 9 |
| 2013 | 6 |
| 2014 | 5 |
| 2015 | 19 |
| 2016 | 8 |
| 2017 | 16 |
| 2022 | 7 |