| Year | Count |
|---|---|
| 1971 | 6 |
| 1975 | 8 |
| 1976 | 7 |
| 1977 | 8 |
| 1978 | 37 |
| 1979 | 68 |
| 1980 | 137 |
| 1981 | 168 |
| 1982 | 262 |
| 1983 | 259 |
| 1984 | 325 |
| 1985 | 338 |
| 1986 | 365 |
| 1987 | 382 |
| 1988 | 412 |
| 1989 | 364 |
| 1990 | 248 |
| 1991 | 282 |
| 1992 | 213 |
| 1993 | 101 |
| 1994 | 93 |
| 1995 | 63 |
| 1996 | 92 |
| 1997 | 100 |
| 1998 | 48 |
| 1999 | 85 |
| 2000 | 65 |
| 2001 | 31 |
| 2002 | 16 |
| 2003 | 735 |
| 2004 | 742 |
| 2005 | 716 |
| 2006 | 505 |
| 2007 | 484 |
| 2008 | 348 |
| 2009 | 121 |
| 2010 | 155 |
| 2011 | 132 |
| 2012 | 143 |
| 2013 | 127 |
| 2014 | 82 |
| 2015 | 100 |
| 2016 | 34 |
| 2017 | 45 |
| 2018 | 13 |
| 2019 | 23 |
| 2020 | 10 |
| 2021 | 20 |
| 2024 | 5 |