| Year | Count |
|---|---|
| 1975 | 7 |
| 1976 | 7 |
| 1978 | 18 |
| 1979 | 16 |
| 1980 | 22 |
| 1981 | 52 |
| 1982 | 35 |
| 1983 | 11 |
| 1984 | 27 |
| 1985 | 24 |
| 1986 | 29 |
| 1987 | 27 |
| 1988 | 20 |
| 1989 | 45 |
| 1990 | 53 |
| 1991 | 33 |
| 1992 | 33 |
| 1993 | 9 |
| 1994 | 27 |
| 1995 | 79 |
| 1996 | 181 |
| 1997 | 210 |
| 1998 | 281 |
| 1999 | 314 |
| 2000 | 437 |
| 2001 | 451 |
| 2002 | 326 |
| 2003 | 264 |
| 2004 | 278 |
| 2005 | 288 |
| 2006 | 314 |
| 2007 | 217 |
| 2008 | 222 |
| 2009 | 161 |
| 2010 | 193 |
| 2011 | 137 |
| 2012 | 126 |
| 2013 | 116 |
| 2014 | 98 |
| 2015 | 125 |
| 2016 | 91 |
| 2017 | 73 |
| 2018 | 73 |
| 2019 | 47 |
| 2020 | 31 |
| 2021 | 34 |
| 2022 | 13 |
| 2023 | 23 |
| 2024 | 12 |