| Year | Count |
|---|---|
| 1981 | 5 |
| 1982 | 5 |
| 1987 | 6 |
| 1988 | 7 |
| 1989 | 10 |
| 1990 | 6 |
| 1991 | 6 |
| 1992 | 9 |
| 1993 | 6 |
| 1994 | 11 |
| 1995 | 16 |
| 1996 | 7 |
| 1997 | 11 |
| 1998 | 13 |
| 1999 | 17 |
| 2000 | 13 |
| 2001 | 22 |
| 2002 | 16 |
| 2003 | 21 |
| 2004 | 17 |
| 2005 | 16 |
| 2006 | 24 |
| 2007 | 19 |
| 2008 | 21 |
| 2009 | 26 |
| 2010 | 56 |
| 2011 | 115 |
| 2012 | 177 |
| 2013 | 271 |
| 2014 | 318 |
| 2015 | 327 |
| 2016 | 1,137 |
| 2017 | 1,191 |
| 2018 | 1,332 |
| 2019 | 844 |
| 2020 | 674 |
| 2021 | 746 |
| 2022 | 792 |
| 2023 | 654 |
| 2024 | 766 |