| Year | Count |
|---|---|
| 1961 | 12 |
| 1962 | 24 |
| 1963 | 25 |
| 1964 | 64 |
| 1965 | 267 |
| 1966 | 219 |
| 1967 | 208 |
| 1968 | 186 |
| 1969 | 124 |
| 1970 | 133 |
| 1971 | 98 |
| 1972 | 66 |
| 1973 | 99 |
| 1974 | 89 |
| 1975 | 74 |
| 1976 | 82 |
| 1977 | 60 |
| 1978 | 88 |
| 1979 | 74 |
| 1980 | 92 |
| 1981 | 76 |
| 1982 | 81 |
| 1983 | 72 |
| 1984 | 69 |
| 1985 | 89 |
| 1986 | 71 |
| 1987 | 110 |
| 1988 | 61 |
| 1989 | 72 |
| 1990 | 91 |
| 1991 | 109 |
| 1992 | 127 |
| 1993 | 77 |
| 1994 | 122 |
| 1995 | 124 |
| 1996 | 82 |
| 1997 | 71 |
| 1998 | 101 |
| 1999 | 70 |
| 2000 | 132 |
| 2001 | 81 |
| 2002 | 125 |
| 2003 | 42 |
| 2004 | 81 |
| 2005 | 63 |
| 2006 | 94 |
| 2007 | 95 |
| 2008 | 87 |
| 2009 | 71 |
| 2010 | 43 |
| 2011 | 54 |
| 2012 | 42 |
| 2013 | 20 |
| 2014 | 14 |
| 2015 | 19 |
| 2016 | 16 |
| 2017 | 10 |
| 2019 | 17 |