| Year | Count |
|---|---|
| 1971 | 7 |
| 1972 | 12 |
| 1973 | 10 |
| 1975 | 15 |
| 1976 | 18 |
| 1977 | 13 |
| 1978 | 5 |
| 1979 | 12 |
| 1980 | 15 |
| 1981 | 14 |
| 1982 | 13 |
| 1983 | 19 |
| 1984 | 11 |
| 1985 | 20 |
| 1986 | 12 |
| 1987 | 32 |
| 1988 | 12 |
| 1992 | 23 |
| 1993 | 97 |
| 1994 | 37 |
| 1995 | 12 |
| 1996 | 22 |
| 1997 | 22 |
| 1998 | 35 |
| 2001 | 19 |
| 2004 | 50 |
| 2005 | 53 |
| 2006 | 12 |
| 2007 | 12 |
| 2008 | 55 |
| 2010 | 8 |
| 2011 | 15 |
| 2015 | 12 |
| 2021 | 5 |