| Year | Count |
|---|---|
| 1971 | 6 |
| 1972 | 7 |
| 1973 | 5 |
| 1974 | 8 |
| 1975 | 12 |
| 1976 | 13 |
| 1977 | 38 |
| 1978 | 47 |
| 1979 | 26 |
| 1980 | 42 |
| 1981 | 13 |
| 1982 | 27 |
| 1983 | 24 |
| 1984 | 22 |
| 1985 | 21 |
| 1986 | 56 |
| 1987 | 81 |
| 1988 | 103 |
| 1989 | 123 |
| 1990 | 140 |
| 1991 | 200 |
| 1992 | 381 |
| 1993 | 398 |
| 1994 | 367 |
| 1995 | 380 |
| 1996 | 625 |
| 1997 | 722 |
| 1998 | 705 |
| 1999 | 685 |
| 2000 | 617 |
| 2001 | 660 |
| 2002 | 550 |
| 2003 | 562 |
| 2004 | 704 |
| 2005 | 672 |
| 2006 | 556 |
| 2007 | 468 |
| 2008 | 318 |
| 2009 | 239 |
| 2010 | 178 |
| 2011 | 210 |
| 2012 | 226 |
| 2013 | 121 |
| 2014 | 149 |
| 2015 | 144 |
| 2016 | 151 |
| 2017 | 227 |
| 2018 | 121 |
| 2019 | 121 |
| 2020 | 113 |
| 2021 | 156 |
| 2022 | 135 |
| 2023 | 117 |
| 2024 | 139 |