| Year | Count |
|---|---|
| 1960 | 5 |
| 1961 | 7 |
| 1964 | 113 |
| 1965 | 230 |
| 1966 | 226 |
| 1967 | 221 |
| 1968 | 184 |
| 1969 | 130 |
| 1970 | 123 |
| 1971 | 113 |
| 1972 | 89 |
| 1973 | 121 |
| 1974 | 81 |
| 1975 | 85 |
| 1976 | 49 |
| 1977 | 38 |
| 1978 | 8 |
| 1979 | 29 |
| 1980 | 24 |
| 1981 | 23 |
| 1982 | 10 |
| 1983 | 32 |
| 1984 | 40 |
| 1985 | 53 |
| 1986 | 64 |
| 1987 | 101 |
| 1988 | 100 |
| 1989 | 87 |
| 1990 | 111 |
| 1991 | 88 |
| 1992 | 130 |
| 1993 | 102 |
| 1994 | 52 |
| 1995 | 29 |
| 1996 | 16 |
| 1997 | 27 |
| 1998 | 10 |
| 1999 | 15 |
| 2000 | 16 |
| 2001 | 12 |
| 2002 | 6 |
| 2003 | 10 |
| 2004 | 5 |
| 2005 | 60 |
| 2006 | 63 |
| 2007 | 24 |
| 2008 | 45 |
| 2009 | 53 |
| 2010 | 13 |
| 2011 | 20 |
| 2012 | 24 |
| 2013 | 10 |
| 2014 | 14 |
| 2015 | 10 |