| Year | Count |
|---|---|
| 1972 | 5 |
| 1973 | 5 |
| 1975 | 8 |
| 1976 | 5 |
| 1977 | 6 |
| 1978 | 27 |
| 1979 | 30 |
| 1980 | 155 |
| 1981 | 245 |
| 1982 | 345 |
| 1983 | 371 |
| 1984 | 478 |
| 1985 | 453 |
| 1986 | 526 |
| 1987 | 519 |
| 1988 | 550 |
| 1989 | 519 |
| 1990 | 452 |
| 1991 | 572 |
| 1992 | 512 |
| 1993 | 440 |
| 1994 | 386 |
| 1995 | 371 |
| 1996 | 418 |
| 1997 | 445 |
| 1998 | 636 |
| 1999 | 453 |
| 2000 | 357 |
| 2001 | 329 |
| 2002 | 227 |
| 2003 | 247 |
| 2004 | 207 |
| 2005 | 178 |
| 2006 | 173 |
| 2007 | 188 |
| 2008 | 187 |
| 2009 | 84 |
| 2010 | 53 |
| 2011 | 82 |
| 2012 | 38 |
| 2013 | 91 |
| 2014 | 45 |
| 2015 | 101 |
| 2016 | 73 |
| 2017 | 58 |
| 2018 | 58 |
| 2019 | 43 |
| 2020 | 26 |
| 2021 | 35 |
| 2022 | 41 |
| 2023 | 26 |
| 2024 | 54 |