| Year | Count |
|---|---|
| 1971 | 10 |
| 1972 | 6 |
| 1973 | 6 |
| 1974 | 36 |
| 1975 | 28 |
| 1976 | 10 |
| 1977 | 67 |
| 1978 | 45 |
| 1979 | 32 |
| 1979 | 86 |
| 1980 | 17 |
| 1980 | 102 |
| 1981 | 10 |
| 1981 | 86 |
| 1982 | 21 |
| 1982 | 144 |
| 1983 | 5 |
| 1983 | 113 |
| 1984 | 156 |
| 1985 | 90 |
| 1986 | 84 |
| 1987 | 65 |
| 1988 | 57 |
| 1989 | 68 |
| 1990 | 87 |
| 1991 | 113 |
| 1992 | 90 |
| 1993 | 120 |
| 1994 | 56 |
| 1995 | 51 |
| 1996 | 56 |
| 1997 | 50 |
| 1998 | 40 |
| 1999 | 81 |
| 2000 | 62 |
| 2001 | 61 |
| 2002 | 35 |
| 2003 | 21 |
| 2004 | 66 |
| 2005 | 44 |
| 2006 | 47 |
| 2007 | 77 |
| 2008 | 56 |
| 2009 | 67 |
| 2010 | 206 |
| 2011 | 147 |
| 2012 | 102 |
| 2013 | 56 |
| 2014 | 60 |
| 2015 | 72 |
| 2016 | 38 |
| 2017 | 56 |
| 2018 | 19 |
| 2019 | 35 |
| 2020 | 32 |