| Year | Count |
|---|---|
| 1969 | 6 |
| 1970 | 5 |
| 1973 | 15 |
| 1975 | 5 |
| 1976 | 10 |
| 1977 | 13 |
| 1980 | 14 |
| 1981 | 15 |
| 1982 | 20 |
| 1983 | 13 |
| 1985 | 6 |
| 1986 | 20 |
| 1987 | 30 |
| 1988 | 12 |
| 1989 | 32 |
| 1990 | 33 |
| 1991 | 11 |
| 1992 | 9 |
| 1993 | 46 |
| 1994 | 54 |
| 1995 | 57 |
| 1996 | 53 |
| 1997 | 89 |
| 1998 | 63 |
| 1999 | 53 |
| 2000 | 140 |
| 2001 | 132 |
| 2002 | 128 |
| 2003 | 214 |
| 2004 | 290 |
| 2005 | 757 |
| 2006 | 713 |
| 2007 | 577 |
| 2008 | 645 |
| 2009 | 605 |
| 2010 | 544 |
| 2011 | 582 |
| 2012 | 518 |
| 2013 | 353 |
| 2014 | 293 |
| 2015 | 334 |
| 2016 | 215 |
| 2017 | 229 |
| 2018 | 149 |
| 2019 | 108 |
| 2020 | 139 |
| 2021 | 54 |
| 2022 | 80 |
| 2023 | 40 |
| 2024 | 47 |