| Year | Count |
|---|---|
| 1970 | 5 |
| 1972 | 6 |
| 1973 | 19 |
| 1974 | 16 |
| 1975 | 24 |
| 1976 | 9 |
| 1977 | 26 |
| 1978 | 42 |
| 1979 | 25 |
| 1980 | 15 |
| 1981 | 11 |
| 1982 | 13 |
| 1983 | 14 |
| 1984 | 18 |
| 1985 | 22 |
| 1986 | 8 |
| 1987 | 5 |
| 1988 | 21 |
| 1989 | 26 |
| 1990 | 12 |
| 1991 | 20 |
| 1992 | 11 |
| 1993 | 21 |
| 1994 | 26 |
| 1995 | 41 |
| 1996 | 45 |
| 1997 | 14 |
| 1998 | 44 |
| 1999 | 30 |
| 2000 | 89 |
| 2001 | 126 |
| 2002 | 112 |
| 2003 | 116 |
| 2004 | 149 |
| 2005 | 169 |
| 2006 | 196 |
| 2007 | 267 |
| 2008 | 318 |
| 2009 | 281 |
| 2010 | 304 |
| 2011 | 261 |
| 2012 | 404 |
| 2013 | 429 |
| 2014 | 472 |
| 2015 | 477 |
| 2016 | 570 |
| 2017 | 504 |
| 2018 | 570 |
| 2019 | 573 |
| 2020 | 399 |
| 2021 | 612 |
| 2022 | 501 |
| 2023 | 595 |
| 2024 | 650 |