| Year | Count |
|---|---|
| 1969 | 6 |
| 1970 | 7 |
| 1971 | 6 |
| 1972 | 7 |
| 1973 | 6 |
| 1974 | 5 |
| 1975 | 12 |
| 1976 | 8 |
| 1977 | 21 |
| 1978 | 16 |
| 1979 | 20 |
| 1980 | 27 |
| 1981 | 47 |
| 1982 | 39 |
| 1983 | 23 |
| 1984 | 61 |
| 1985 | 111 |
| 1986 | 57 |
| 1987 | 76 |
| 1988 | 95 |
| 1989 | 47 |
| 1990 | 53 |
| 1991 | 73 |
| 1992 | 54 |
| 1993 | 49 |
| 1994 | 57 |
| 1995 | 48 |
| 1996 | 58 |
| 1997 | 58 |
| 1998 | 61 |
| 1999 | 50 |
| 2000 | 71 |
| 2001 | 192 |
| 2002 | 135 |
| 2003 | 162 |
| 2004 | 239 |
| 2005 | 274 |
| 2006 | 203 |
| 2007 | 190 |
| 2008 | 208 |
| 2009 | 83 |
| 2010 | 59 |
| 2011 | 69 |
| 2012 | 49 |
| 2013 | 28 |
| 2014 | 11 |
| 2015 | 42 |
| 2016 | 28 |
| 2017 | 45 |
| 2018 | 34 |
| 2019 | 45 |
| 2020 | 59 |
| 2021 | 11 |
| 2022 | 25 |
| 2023 | 18 |
| 2024 | 28 |