| Year | Count |
|---|---|
| 1970 | 31 |
| 1971 | 26 |
| 1972 | 5 |
| 1973 | 5 |
| 1974 | 5 |
| 1975 | 10 |
| 1976 | 19 |
| 1977 | 87 |
| 1978 | 55 |
| 1979 | 46 |
| 1980 | 56 |
| 1981 | 34 |
| 1982 | 36 |
| 1983 | 85 |
| 1984 | 165 |
| 1985 | 166 |
| 1986 | 130 |
| 1987 | 130 |
| 1988 | 78 |
| 1989 | 72 |
| 1990 | 58 |
| 1991 | 126 |
| 1992 | 114 |
| 1993 | 79 |
| 1994 | 110 |
| 1995 | 100 |
| 1996 | 118 |
| 1997 | 99 |
| 1998 | 152 |
| 1999 | 164 |
| 2000 | 191 |
| 2001 | 231 |
| 2002 | 218 |
| 2003 | 290 |
| 2004 | 249 |
| 2005 | 281 |
| 2006 | 287 |
| 2007 | 350 |
| 2008 | 492 |
| 2009 | 363 |
| 2010 | 393 |
| 2011 | 221 |
| 2012 | 258 |
| 2013 | 197 |
| 2014 | 174 |
| 2015 | 121 |
| 2016 | 94 |
| 2017 | 5 |
| 2018 | 5 |
| 2019 | 6 |
| 2020 | 5 |
| 2022 | 7 |
| 2023 | 6 |