| Year | Count |
|---|---|
| 1971 | 7 |
| 1972 | 18 |
| 1973 | 17 |
| 1974 | 7 |
| 1975 | 13 |
| 1976 | 17 |
| 1977 | 21 |
| 1978 | 25 |
| 1979 | 30 |
| 1980 | 19 |
| 1981 | 17 |
| 1982 | 13 |
| 1983 | 15 |
| 1984 | 7 |
| 1985 | 5 |
| 1986 | 7 |
| 1987 | 16 |
| 1988 | 6 |
| 1989 | 28 |
| 1990 | 5 |
| 1991 | 12 |
| 1992 | 43 |
| 1993 | 31 |
| 1994 | 67 |
| 1995 | 69 |
| 1996 | 94 |
| 1997 | 117 |
| 1998 | 167 |
| 1999 | 167 |
| 2000 | 268 |
| 2001 | 312 |
| 2002 | 245 |
| 2003 | 290 |
| 2004 | 339 |
| 2005 | 470 |
| 2006 | 458 |
| 2007 | 431 |
| 2008 | 483 |
| 2009 | 445 |
| 2010 | 412 |
| 2011 | 400 |
| 2012 | 514 |
| 2013 | 332 |
| 2014 | 269 |
| 2015 | 302 |
| 2016 | 334 |
| 2017 | 367 |
| 2018 | 248 |
| 2019 | 267 |
| 2020 | 304 |
| 2021 | 367 |
| 2022 | 333 |
| 2023 | 305 |
| 2024 | 298 |