| Year | Count |
|---|---|
| 1971 | 8 |
| 1972 | 5 |
| 1973 | 5 |
| 1975 | 18 |
| 1977 | 32 |
| 1978 | 15 |
| 1979 | 39 |
| 1980 | 43 |
| 1981 | 53 |
| 1982 | 23 |
| 1983 | 47 |
| 1984 | 64 |
| 1985 | 19 |
| 1986 | 76 |
| 1987 | 63 |
| 1988 | 78 |
| 1989 | 56 |
| 1990 | 75 |
| 1991 | 90 |
| 1992 | 38 |
| 1993 | 44 |
| 1994 | 22 |
| 1995 | 28 |
| 1996 | 15 |
| 1997 | 15 |
| 1998 | 23 |
| 1999 | 21 |
| 2000 | 15 |
| 2001 | 8 |
| 2002 | 15 |
| 2004 | 5 |
| 2005 | 10 |
| 2006 | 17 |
| 2007 | 8 |
| 2009 | 17 |
| 2010 | 10 |
| 2011 | 18 |