| Year | Count |
|---|---|
| 1978 | 5 |
| 1981 | 5 |
| 1982 | 5 |
| 1985 | 5 |
| 1987 | 6 |
| 1988 | 17 |
| 1989 | 10 |
| 1990 | 30 |
| 1991 | 35 |
| 1992 | 44 |
| 1993 | 40 |
| 1994 | 32 |
| 1995 | 106 |
| 1996 | 87 |
| 1997 | 54 |
| 1998 | 140 |
| 1999 | 139 |
| 2000 | 161 |
| 2001 | 303 |
| 2002 | 262 |
| 2003 | 382 |
| 2004 | 437 |
| 2005 | 407 |
| 2006 | 443 |
| 2007 | 611 |
| 2008 | 523 |
| 2009 | 604 |
| 2010 | 920 |
| 2011 | 2,247 |
| 2012 | 3,643 |
| 2013 | 5,370 |
| 2014 | 6,125 |
| 2015 | 7,194 |
| 2016 | 8,323 |
| 2017 | 8,504 |
| 2018 | 8,520 |
| 2019 | 7,678 |
| 2020 | 6,354 |
| 2021 | 7,275 |
| 2022 | 7,496 |
| 2023 | 6,890 |
| 2024 | 6,709 |