| Year | Count |
|---|---|
| 1969 | 6 |
| 1970 | 7 |
| 1975 | 14 |
| 1976 | 12 |
| 1977 | 7 |
| 1978 | 6 |
| 1979 | 27 |
| 1980 | 14 |
| 1981 | 27 |
| 1982 | 28 |
| 1983 | 23 |
| 1984 | 19 |
| 1985 | 18 |
| 1986 | 57 |
| 1987 | 41 |
| 1988 | 41 |
| 1989 | 48 |
| 1990 | 81 |
| 1991 | 54 |
| 1992 | 57 |
| 1993 | 89 |
| 1994 | 112 |
| 1995 | 69 |
| 1996 | 97 |
| 1997 | 106 |
| 1998 | 123 |
| 1999 | 149 |
| 2000 | 163 |
| 2001 | 191 |
| 2002 | 166 |
| 2003 | 232 |
| 2004 | 328 |
| 2005 | 253 |
| 2006 | 307 |
| 2007 | 281 |
| 2008 | 276 |
| 2009 | 313 |
| 2010 | 268 |
| 2011 | 201 |
| 2012 | 248 |
| 2013 | 259 |
| 2014 | 272 |
| 2015 | 286 |
| 2016 | 214 |
| 2017 | 176 |
| 2018 | 174 |
| 2019 | 142 |
| 2020 | 77 |
| 2021 | 223 |
| 2022 | 126 |
| 2023 | 99 |
| 2024 | 107 |