| Year | Count |
|---|---|
| 1956 | 14 |
| 1957 | 20 |
| 1959 | 50 |
| 1960 | 56 |
| 1961 | 37 |
| 1962 | 41 |
| 1963 | 42 |
| 1964 | 68 |
| 1965 | 74 |
| 1966 | 127 |
| 1967 | 285 |
| 1968 | 268 |
| 1969 | 241 |
| 1970 | 294 |
| 1971 | 310 |
| 1972 | 246 |
| 1973 | 250 |
| 1974 | 217 |
| 1975 | 207 |
| 1976 | 151 |
| 1977 | 120 |
| 1978 | 108 |
| 1979 | 77 |
| 1980 | 40 |
| 1981 | 88 |
| 1982 | 94 |
| 1983 | 50 |
| 1984 | 42 |
| 1985 | 61 |
| 1986 | 33 |
| 1987 | 43 |
| 1988 | 36 |
| 1989 | 24 |
| 1990 | 40 |
| 1991 | 8 |
| 1992 | 28 |
| 1993 | 48 |
| 1994 | 24 |
| 1995 | 37 |
| 1996 | 12 |
| 1997 | 18 |
| 1998 | 9 |
| 1999 | 11 |
| 2000 | 25 |
| 2001 | 34 |
| 2002 | 6 |
| 2003 | 26 |
| 2004 | 63 |
| 2005 | 44 |
| 2006 | 37 |
| 2007 | 16 |
| 2008 | 31 |
| 2009 | 11 |
| 2011 | 6 |
| 2013 | 5 |