| Year | Count |
|---|---|
| 1921 | 10 |
| 1939 | 7 |
| 1940 | 5 |
| 1951 | 12 |
| 1967 | 5 |
| 1968 | 25 |
| 1969 | 11 |
| 1970 | 30 |
| 1971 | 15 |
| 1972 | 15 |
| 1973 | 34 |
| 1974 | 67 |
| 1975 | 63 |
| 1976 | 61 |
| 1977 | 119 |
| 1978 | 173 |
| 1979 | 212 |
| 1980 | 190 |
| 1981 | 180 |
| 1982 | 157 |
| 1983 | 166 |
| 1984 | 154 |
| 1985 | 186 |
| 1986 | 122 |
| 1987 | 148 |
| 1988 | 99 |
| 1989 | 123 |
| 1990 | 129 |
| 1991 | 117 |
| 1992 | 107 |
| 1993 | 76 |
| 1994 | 43 |
| 1995 | 28 |
| 1996 | 36 |
| 1997 | 24 |
| 1998 | 52 |
| 1999 | 28 |
| 2000 | 19 |
| 2001 | 42 |
| 2002 | 19 |
| 2003 | 37 |
| 2004 | 51 |
| 2005 | 20 |
| 2006 | 26 |
| 2007 | 17 |
| 2008 | 67 |
| 2009 | 23 |
| 2010 | 35 |
| 2011 | 78 |
| 2012 | 47 |
| 2013 | 20 |
| 2014 | 6 |
| 2015 | 73 |
| 2016 | 42 |
| 2017 | 24 |
| 2018 | 28 |
| 2019 | 5 |
| 2020 | 18 |