| Year | Count |
|---|---|
| 1971 | 10 |
| 1974 | 5 |
| 1976 | 10 |
| 1977 | 12 |
| 1978 | 17 |
| 1979 | 53 |
| 1980 | 62 |
| 1981 | 52 |
| 1982 | 91 |
| 1983 | 66 |
| 1984 | 113 |
| 1985 | 116 |
| 1986 | 151 |
| 1987 | 191 |
| 1988 | 195 |
| 1989 | 374 |
| 1990 | 351 |
| 1991 | 357 |
| 1992 | 438 |
| 1993 | 360 |
| 1994 | 409 |
| 1995 | 309 |
| 1996 | 289 |
| 1997 | 275 |
| 1998 | 342 |
| 1999 | 229 |
| 2000 | 318 |
| 2001 | 312 |
| 2002 | 196 |
| 2003 | 213 |
| 2004 | 208 |
| 2005 | 224 |
| 2006 | 225 |
| 2007 | 152 |
| 2008 | 197 |
| 2009 | 142 |
| 2010 | 97 |
| 2011 | 123 |
| 2012 | 53 |
| 2013 | 81 |
| 2014 | 53 |
| 2015 | 47 |
| 2016 | 34 |
| 2017 | 32 |
| 2018 | 49 |
| 2019 | 23 |
| 2020 | 15 |
| 2021 | 17 |
| 2022 | 12 |
| 2023 | 12 |