| Year | Count |
|---|---|
| 1951 | 6 |
| 1952 | 13 |
| 1955 | 6 |
| 1959 | 5 |
| 1964 | 5 |
| 1965 | 5 |
| 1966 | 5 |
| 1967 | 14 |
| 1968 | 19 |
| 1969 | 67 |
| 1970 | 81 |
| 1971 | 37 |
| 1972 | 43 |
| 1973 | 59 |
| 1974 | 41 |
| 1975 | 29 |
| 1976 | 31 |
| 1977 | 49 |
| 1978 | 51 |
| 1979 | 43 |
| 1980 | 53 |
| 1981 | 54 |
| 1982 | 77 |
| 1983 | 108 |
| 1984 | 130 |
| 1985 | 147 |
| 1986 | 154 |
| 1987 | 169 |
| 1988 | 228 |
| 1989 | 177 |
| 1990 | 190 |
| 1991 | 221 |
| 1992 | 159 |
| 1993 | 196 |
| 1994 | 131 |
| 1995 | 56 |
| 1996 | 113 |
| 1997 | 139 |
| 1998 | 83 |
| 1999 | 65 |
| 2000 | 23 |
| 2001 | 64 |
| 2002 | 52 |
| 2003 | 20 |
| 2004 | 47 |
| 2005 | 57 |
| 2006 | 37 |
| 2007 | 38 |
| 2008 | 67 |
| 2009 | 19 |
| 2010 | 12 |
| 2011 | 6 |
| 2012 | 8 |
| 2014 | 5 |
| 2015 | 15 |