| Year | Count |
|---|---|
| 1978 | 6 |
| 1979 | 5 |
| 1980 | 6 |
| 1981 | 10 |
| 1982 | 19 |
| 1983 | 23 |
| 1984 | 36 |
| 1985 | 66 |
| 1986 | 91 |
| 1987 | 90 |
| 1988 | 73 |
| 1989 | 168 |
| 1990 | 207 |
| 1991 | 188 |
| 1992 | 219 |
| 1993 | 151 |
| 1994 | 125 |
| 1995 | 244 |
| 1996 | 197 |
| 1997 | 310 |
| 1998 | 315 |
| 1999 | 345 |
| 2000 | 301 |
| 2001 | 247 |
| 2002 | 237 |
| 2003 | 257 |
| 2004 | 292 |
| 2005 | 324 |
| 2006 | 352 |
| 2007 | 477 |
| 2008 | 466 |
| 2009 | 398 |
| 2010 | 472 |
| 2011 | 467 |
| 2012 | 495 |
| 2013 | 395 |
| 2014 | 451 |
| 2015 | 512 |
| 2016 | 353 |
| 2017 | 336 |
| 2018 | 257 |
| 2019 | 351 |
| 2020 | 387 |
| 2021 | 401 |
| 2022 | 321 |
| 2023 | 362 |
| 2024 | 361 |