| Year | Count |
|---|---|
| 1977 | 8 |
| 1981 | 6 |
| 1983 | 11 |
| 1986 | 10 |
| 1987 | 10 |
| 1988 | 9 |
| 1990 | 16 |
| 1991 | 114 |
| 1992 | 20 |
| 1993 | 10 |
| 1994 | 10 |
| 1995 | 10 |
| 1996 | 29 |
| 1997 | 26 |
| 1998 | 120 |
| 1999 | 66 |
| 2000 | 128 |
| 2001 | 140 |
| 2002 | 103 |
| 2003 | 88 |
| 2004 | 285 |
| 2005 | 316 |
| 2006 | 237 |
| 2007 | 642 |
| 2008 | 519 |
| 2009 | 321 |
| 2010 | 217 |
| 2011 | 233 |
| 2012 | 316 |
| 2013 | 166 |
| 2014 | 104 |
| 2015 | 247 |
| 2016 | 234 |
| 2017 | 276 |
| 2018 | 179 |
| 2019 | 173 |
| 2020 | 157 |
| 2021 | 150 |
| 2022 | 152 |
| 2023 | 187 |
| 2024 | 144 |