| Year | Count |
|---|---|
| 1971 | 5 |
| 1975 | 19 |
| 1976 | 100 |
| 1977 | 48 |
| 1978 | 53 |
| 1979 | 20 |
| 1980 | 6 |
| 1981 | 35 |
| 1982 | 30 |
| 1983 | 37 |
| 1984 | 27 |
| 1985 | 34 |
| 1986 | 24 |
| 1987 | 20 |
| 1988 | 23 |
| 1989 | 37 |
| 1990 | 55 |
| 1991 | 87 |
| 1992 | 109 |
| 1993 | 156 |
| 1994 | 144 |
| 1995 | 107 |
| 1996 | 164 |
| 1997 | 266 |
| 1998 | 357 |
| 1999 | 353 |
| 2000 | 373 |
| 2001 | 429 |
| 2002 | 367 |
| 2003 | 410 |
| 2004 | 572 |
| 2005 | 632 |
| 2006 | 479 |
| 2007 | 530 |
| 2008 | 478 |
| 2009 | 420 |
| 2010 | 406 |
| 2011 | 409 |
| 2012 | 448 |
| 2013 | 481 |
| 2014 | 313 |
| 2015 | 84 |
| 2016 | 26 |
| 2017 | 5 |
| 2019 | 24 |
| 2020 | 14 |
| 2021 | 91 |
| 2022 | 87 |
| 2023 | 145 |
| 2024 | 223 |