| Year | Count |
|---|---|
| 1971 | 9 |
| 1973 | 8 |
| 1974 | 14 |
| 1975 | 19 |
| 1976 | 31 |
| 1977 | 24 |
| 1978 | 52 |
| 1979 | 64 |
| 1980 | 51 |
| 1981 | 87 |
| 1982 | 115 |
| 1983 | 98 |
| 1984 | 80 |
| 1985 | 98 |
| 1986 | 95 |
| 1987 | 129 |
| 1988 | 133 |
| 1989 | 150 |
| 1990 | 177 |
| 1991 | 227 |
| 1992 | 252 |
| 1993 | 180 |
| 1994 | 259 |
| 1995 | 265 |
| 1996 | 284 |
| 1997 | 323 |
| 1998 | 386 |
| 1999 | 463 |
| 2000 | 471 |
| 2001 | 537 |
| 2002 | 381 |
| 2003 | 339 |
| 2004 | 371 |
| 2005 | 406 |
| 2006 | 401 |
| 2007 | 364 |
| 2008 | 454 |
| 2009 | 380 |
| 2010 | 445 |
| 2011 | 425 |
| 2012 | 466 |
| 2013 | 520 |
| 2014 | 640 |
| 2015 | 667 |
| 2016 | 633 |
| 2017 | 572 |
| 2018 | 503 |
| 2019 | 469 |
| 2020 | 422 |
| 2021 | 422 |
| 2022 | 344 |
| 2023 | 430 |
| 2024 | 492 |