| Year | Count |
|---|---|
| 1972 | 6 |
| 1977 | 10 |
| 1979 | 14 |
| 1980 | 12 |
| 1981 | 11 |
| 1982 | 20 |
| 1983 | 15 |
| 1984 | 10 |
| 1985 | 12 |
| 1986 | 22 |
| 1987 | 23 |
| 1988 | 25 |
| 1989 | 33 |
| 1990 | 106 |
| 1991 | 88 |
| 1992 | 70 |
| 1993 | 91 |
| 1994 | 75 |
| 1995 | 77 |
| 1996 | 66 |
| 1997 | 85 |
| 1998 | 101 |
| 1999 | 63 |
| 2000 | 41 |
| 2001 | 80 |
| 2002 | 88 |
| 2003 | 127 |
| 2004 | 113 |
| 2005 | 165 |
| 2006 | 196 |
| 2007 | 234 |
| 2008 | 325 |
| 2009 | 268 |
| 2010 | 326 |
| 2011 | 453 |
| 2012 | 575 |
| 2013 | 712 |
| 2014 | 838 |
| 2015 | 906 |
| 2016 | 1,210 |
| 2017 | 1,411 |
| 2018 | 1,389 |
| 2019 | 1,560 |
| 2020 | 1,909 |
| 2021 | 1,911 |
| 2022 | 1,887 |
| 2023 | 1,799 |
| 2024 | 1,709 |