| Year | Count |
|---|---|
| 1972 | 6 |
| 1975 | 5 |
| 1977 | 6 |
| 1980 | 8 |
| 1981 | 11 |
| 1982 | 7 |
| 1985 | 12 |
| 1986 | 8 |
| 1987 | 17 |
| 1988 | 21 |
| 1989 | 11 |
| 1990 | 59 |
| 1991 | 51 |
| 1992 | 57 |
| 1993 | 68 |
| 1994 | 68 |
| 1995 | 112 |
| 1996 | 127 |
| 1997 | 132 |
| 1998 | 143 |
| 1999 | 278 |
| 2000 | 277 |
| 2001 | 288 |
| 2002 | 390 |
| 2003 | 407 |
| 2004 | 500 |
| 2005 | 450 |
| 2006 | 468 |
| 2007 | 464 |
| 2008 | 452 |
| 2009 | 444 |
| 2010 | 433 |
| 2011 | 357 |
| 2012 | 391 |
| 2013 | 406 |
| 2014 | 377 |
| 2015 | 410 |
| 2016 | 339 |
| 2017 | 387 |
| 2018 | 331 |
| 2019 | 278 |
| 2020 | 217 |
| 2021 | 322 |
| 2022 | 245 |
| 2023 | 259 |
| 2024 | 242 |