| Year | Count |
|---|---|
| 1972 | 5 |
| 1973 | 10 |
| 1975 | 5 |
| 1978 | 5 |
| 1979 | 23 |
| 1980 | 37 |
| 1981 | 24 |
| 1982 | 57 |
| 1983 | 19 |
| 1985 | 5 |
| 1986 | 22 |
| 1987 | 60 |
| 1988 | 22 |
| 1989 | 51 |
| 1990 | 54 |
| 1991 | 80 |
| 1992 | 69 |
| 1993 | 78 |
| 1994 | 71 |
| 1995 | 81 |
| 1996 | 149 |
| 1997 | 154 |
| 1998 | 163 |
| 1999 | 173 |
| 2000 | 153 |
| 2001 | 140 |
| 2002 | 114 |
| 2003 | 119 |
| 2004 | 202 |
| 2005 | 247 |
| 2006 | 305 |
| 2007 | 332 |
| 2008 | 368 |
| 2009 | 319 |
| 2010 | 290 |
| 2011 | 208 |
| 2012 | 212 |
| 2013 | 157 |
| 2014 | 129 |
| 2015 | 145 |
| 2016 | 92 |
| 2017 | 54 |
| 2018 | 51 |
| 2019 | 40 |
| 2020 | 93 |
| 2021 | 91 |
| 2022 | 96 |
| 2023 | 70 |
| 2024 | 32 |