| Year | Count |
|---|---|
| 1971 | 44 |
| 1972 | 108 |
| 1973 | 80 |
| 1974 | 123 |
| 1975 | 151 |
| 1976 | 98 |
| 1977 | 83 |
| 1978 | 89 |
| 1979 | 63 |
| 1980 | 37 |
| 1981 | 26 |
| 1982 | 30 |
| 1983 | 40 |
| 1984 | 20 |
| 1985 | 79 |
| 1986 | 48 |
| 1987 | 33 |
| 1988 | 8 |
| 1989 | 32 |
| 1990 | 40 |
| 1991 | 62 |
| 1992 | 111 |
| 1993 | 74 |
| 1994 | 89 |
| 1995 | 146 |
| 1996 | 180 |
| 1997 | 239 |
| 1998 | 244 |
| 1999 | 215 |
| 2000 | 294 |
| 2001 | 355 |
| 2002 | 423 |
| 2003 | 579 |
| 2004 | 648 |
| 2005 | 639 |
| 2006 | 621 |
| 2007 | 666 |
| 2008 | 489 |
| 2009 | 489 |
| 2010 | 439 |
| 2011 | 483 |
| 2012 | 487 |
| 2013 | 394 |
| 2014 | 498 |
| 2015 | 511 |
| 2016 | 502 |
| 2017 | 578 |
| 2018 | 334 |
| 2019 | 357 |
| 2020 | 306 |
| 2021 | 314 |
| 2022 | 280 |
| 2023 | 254 |
| 2024 | 274 |