| Year | Count |
|---|---|
| 1970 | 9 |
| 1971 | 9 |
| 1972 | 18 |
| 1973 | 16 |
| 1975 | 7 |
| 1976 | 13 |
| 1977 | 5 |
| 1978 | 7 |
| 1979 | 10 |
| 1980 | 8 |
| 1981 | 6 |
| 1982 | 10 |
| 1983 | 7 |
| 1984 | 11 |
| 1985 | 18 |
| 1986 | 18 |
| 1987 | 18 |
| 1988 | 14 |
| 1989 | 29 |
| 1990 | 93 |
| 1991 | 79 |
| 1992 | 69 |
| 1993 | 74 |
| 1994 | 19 |
| 1995 | 42 |
| 1996 | 58 |
| 1997 | 62 |
| 1998 | 41 |
| 1999 | 25 |
| 2000 | 20 |
| 2001 | 83 |
| 2002 | 30 |
| 2003 | 18 |
| 2004 | 429 |
| 2005 | 708 |
| 2006 | 379 |
| 2007 | 319 |
| 2008 | 456 |
| 2009 | 178 |
| 2010 | 197 |
| 2011 | 138 |
| 2012 | 136 |
| 2013 | 90 |
| 2014 | 85 |
| 2015 | 144 |
| 2016 | 103 |
| 2017 | 162 |
| 2018 | 82 |
| 2019 | 110 |
| 2020 | 112 |
| 2021 | 129 |
| 2022 | 197 |
| 2023 | 157 |
| 2024 | 181 |