| Year | Count |
|---|---|
| 1988 | 12 |
| 1990 | 10 |
| 1991 | 19 |
| 1992 | 42 |
| 1993 | 134 |
| 1994 | 262 |
| 1995 | 308 |
| 1996 | 505 |
| 1997 | 593 |
| 1998 | 535 |
| 1999 | 561 |
| 2000 | 472 |
| 2001 | 486 |
| 2002 | 424 |
| 2003 | 430 |
| 2004 | 446 |
| 2005 | 387 |
| 2006 | 401 |
| 2007 | 565 |
| 2008 | 598 |
| 2009 | 358 |
| 2010 | 238 |
| 2011 | 216 |
| 2012 | 122 |
| 2013 | 139 |
| 2014 | 144 |
| 2015 | 92 |
| 2016 | 46 |
| 2017 | 42 |
| 2018 | 18 |
| 2019 | 31 |
| 2020 | 17 |
| 2021 | 7 |
| 2022 | 6 |
| 2023 | 7 |