| Year | Count |
|---|---|
| 1968 | 5 |
| 1969 | 5 |
| 1970 | 5 |
| 1971 | 10 |
| 1972 | 5 |
| 1973 | 6 |
| 1974 | 7 |
| 1975 | 9 |
| 1976 | 7 |
| 1978 | 29 |
| 1979 | 114 |
| 1980 | 50 |
| 1981 | 73 |
| 1982 | 54 |
| 1983 | 39 |
| 1984 | 51 |
| 1985 | 20 |
| 1986 | 40 |
| 1987 | 39 |
| 1988 | 32 |
| 1989 | 34 |
| 1990 | 32 |
| 1991 | 24 |
| 1992 | 13 |
| 1993 | 20 |
| 1994 | 18 |
| 1995 | 51 |
| 1996 | 32 |
| 1997 | 35 |
| 1998 | 20 |
| 1999 | 64 |
| 2000 | 42 |
| 2001 | 51 |
| 2002 | 36 |
| 2003 | 60 |
| 2004 | 36 |
| 2005 | 243 |
| 2006 | 137 |
| 2007 | 136 |
| 2008 | 133 |
| 2009 | 48 |
| 2010 | 48 |
| 2011 | 53 |
| 2012 | 64 |
| 2013 | 71 |
| 2014 | 88 |
| 2015 | 92 |
| 2016 | 80 |
| 2017 | 118 |
| 2018 | 83 |
| 2019 | 31 |
| 2020 | 57 |
| 2021 | 14 |
| 2022 | 61 |
| 2023 | 32 |
| 2024 | 29 |