| Year | Count |
|---|---|
| 1964 | 6 |
| 1967 | 15 |
| 1968 | 30 |
| 1969 | 68 |
| 1970 | 52 |
| 1971 | 92 |
| 1972 | 47 |
| 1973 | 72 |
| 1974 | 85 |
| 1975 | 56 |
| 1976 | 53 |
| 1977 | 119 |
| 1978 | 161 |
| 1979 | 175 |
| 1980 | 98 |
| 1981 | 116 |
| 1982 | 78 |
| 1983 | 40 |
| 1984 | 76 |
| 1985 | 109 |
| 1986 | 174 |
| 1987 | 315 |
| 1988 | 343 |
| 1989 | 379 |
| 1990 | 295 |
| 1991 | 302 |
| 1992 | 320 |
| 1993 | 254 |
| 1994 | 228 |
| 1995 | 186 |
| 1996 | 233 |
| 1997 | 259 |
| 1998 | 229 |
| 1999 | 171 |
| 2000 | 150 |
| 2001 | 172 |
| 2002 | 113 |
| 2003 | 115 |
| 2004 | 129 |
| 2005 | 108 |
| 2006 | 143 |
| 2007 | 129 |
| 2008 | 144 |
| 2009 | 68 |
| 2010 | 59 |
| 2011 | 68 |
| 2012 | 29 |
| 2013 | 20 |
| 2014 | 21 |
| 2015 | 16 |
| 2016 | 31 |
| 2017 | 34 |
| 2018 | 12 |
| 2019 | 19 |
| 2021 | 5 |