| Year | Count |
|---|---|
| 1971 | 7 |
| 1972 | 7 |
| 1974 | 19 |
| 1975 | 25 |
| 1976 | 14 |
| 1977 | 5 |
| 1978 | 16 |
| 1979 | 20 |
| 1981 | 5 |
| 1982 | 22 |
| 1984 | 15 |
| 1985 | 59 |
| 1986 | 15 |
| 1987 | 26 |
| 1988 | 12 |
| 1989 | 53 |
| 1990 | 52 |
| 1991 | 94 |
| 1992 | 131 |
| 1993 | 83 |
| 1994 | 109 |
| 1995 | 39 |
| 1996 | 85 |
| 1997 | 140 |
| 1998 | 148 |
| 1999 | 170 |
| 2000 | 189 |
| 2001 | 185 |
| 2002 | 163 |
| 2003 | 432 |
| 2004 | 1,454 |
| 2005 | 1,782 |
| 2006 | 3,486 |
| 2007 | 3,216 |
| 2008 | 2,975 |
| 2009 | 2,369 |
| 2010 | 1,893 |
| 2011 | 1,956 |
| 2012 | 1,842 |
| 2013 | 1,637 |
| 2014 | 1,475 |
| 2015 | 1,354 |
| 2016 | 1,187 |
| 2017 | 1,119 |
| 2018 | 959 |
| 2019 | 893 |
| 2020 | 638 |
| 2021 | 668 |
| 2022 | 558 |
| 2023 | 518 |
| 2024 | 477 |