| Year | Count |
|---|---|
| 1977 | 5 |
| 1978 | 31 |
| 1978 | 14 |
| 1979 | 26 |
| 1980 | 22 |
| 1982 | 8 |
| 1983 | 13 |
| 1984 | 29 |
| 1985 | 36 |
| 1986 | 25 |
| 1987 | 40 |
| 1988 | 72 |
| 1989 | 79 |
| 1990 | 6 |
| 1990 | 126 |
| 1991 | 17 |
| 1991 | 140 |
| 1992 | 15 |
| 1992 | 261 |
| 1993 | 301 |
| 1994 | 296 |
| 1995 | 10 |
| 1995 | 304 |
| 1996 | 353 |
| 1997 | 14 |
| 1997 | 369 |
| 1998 | 441 |
| 1999 | 6 |
| 1999 | 481 |
| 2000 | 458 |
| 2001 | 461 |
| 2002 | 12 |
| 2002 | 423 |
| 2003 | 514 |
| 2004 | 534 |
| 2005 | 471 |
| 2006 | 378 |
| 2007 | 311 |
| 2008 | 324 |
| 2009 | 332 |
| 2010 | 195 |
| 2011 | 173 |
| 2012 | 120 |
| 2013 | 126 |
| 2014 | 113 |
| 2015 | 58 |
| 2016 | 43 |
| 2017 | 66 |
| 2018 | 33 |
| 2019 | 17 |
| 2020 | 7 |
| 2021 | 5 |
| 2022 | 19 |
| 2023 | 23 |
| 2024 | 23 |