| Year | Count |
|---|---|
| 1964 | 5 |
| 1970 | 10 |
| 1971 | 12 |
| 1972 | 7 |
| 1973 | 11 |
| 1974 | 14 |
| 1975 | 22 |
| 1976 | 19 |
| 1977 | 46 |
| 1978 | 78 |
| 1979 | 82 |
| 1980 | 90 |
| 1981 | 44 |
| 1982 | 39 |
| 1983 | 76 |
| 1984 | 97 |
| 1985 | 90 |
| 1986 | 110 |
| 1987 | 97 |
| 1988 | 94 |
| 1989 | 94 |
| 1990 | 85 |
| 1991 | 108 |
| 1992 | 83 |
| 1993 | 91 |
| 1994 | 85 |
| 1995 | 68 |
| 1996 | 53 |
| 1997 | 60 |
| 1998 | 49 |
| 1999 | 50 |
| 2000 | 40 |
| 2001 | 38 |
| 2002 | 27 |
| 2003 | 30 |
| 2004 | 22 |
| 2005 | 17 |
| 2006 | 8 |
| 2007 | 19 |
| 2008 | 15 |
| 2009 | 7 |
| 2010 | 12 |
| 2011 | 5 |
| 2013 | 5 |