| Year | Count |
|---|---|
| 1972 | 6 |
| 1977 | 10 |
| 1979 | 14 |
| 1980 | 12 |
| 1981 | 5 |
| 1982 | 20 |
| 1983 | 15 |
| 1984 | 10 |
| 1985 | 12 |
| 1986 | 16 |
| 1987 | 18 |
| 1988 | 20 |
| 1989 | 16 |
| 1990 | 34 |
| 1991 | 33 |
| 1992 | 28 |
| 1993 | 27 |
| 1994 | 33 |
| 1995 | 23 |
| 1996 | 34 |
| 1997 | 36 |
| 1998 | 44 |
| 1999 | 25 |
| 2000 | 30 |
| 2001 | 31 |
| 2002 | 33 |
| 2003 | 45 |
| 2004 | 37 |
| 2005 | 47 |
| 2006 | 58 |
| 2007 | 50 |
| 2008 | 67 |
| 2009 | 67 |
| 2010 | 81 |
| 2011 | 78 |
| 2012 | 88 |
| 2013 | 99 |
| 2014 | 114 |
| 2015 | 125 |
| 2016 | 318 |
| 2017 | 369 |
| 2018 | 360 |
| 2019 | 316 |
| 2020 | 340 |
| 2021 | 264 |
| 2022 | 300 |
| 2023 | 238 |
| 2024 | 240 |