| Year | Count |
|---|---|
| 1968 | 6 |
| 1971 | 5 |
| 1972 | 6 |
| 1973 | 6 |
| 1974 | 5 |
| 1975 | 13 |
| 1976 | 21 |
| 1977 | 11 |
| 1978 | 59 |
| 1979 | 85 |
| 1980 | 155 |
| 1981 | 86 |
| 1982 | 126 |
| 1983 | 178 |
| 1984 | 201 |
| 1985 | 287 |
| 1986 | 402 |
| 1987 | 360 |
| 1988 | 406 |
| 1989 | 468 |
| 1990 | 367 |
| 1991 | 431 |
| 1992 | 264 |
| 1993 | 260 |
| 1994 | 217 |
| 1995 | 196 |
| 1996 | 294 |
| 1997 | 275 |
| 1998 | 280 |
| 1999 | 199 |
| 2000 | 159 |
| 2001 | 230 |
| 2002 | 146 |
| 2003 | 193 |
| 2004 | 270 |
| 2005 | 284 |
| 2006 | 253 |
| 2007 | 144 |
| 2008 | 199 |
| 2009 | 114 |
| 2010 | 127 |
| 2011 | 115 |
| 2012 | 106 |
| 2013 | 109 |
| 2014 | 44 |
| 2015 | 102 |
| 2016 | 124 |
| 2017 | 107 |
| 2018 | 113 |
| 2019 | 107 |
| 2020 | 112 |
| 2021 | 67 |
| 2022 | 70 |
| 2023 | 90 |
| 2024 | 63 |