| Year | Count |
|---|---|
| 1964 | 18 |
| 1965 | 17 |
| 1966 | 146 |
| 1967 | 181 |
| 1968 | 214 |
| 1969 | 345 |
| 1970 | 652 |
| 1971 | 1,268 |
| 1972 | 1,485 |
| 1973 | 1,361 |
| 1974 | 1,687 |
| 1975 | 1,392 |
| 1976 | 1,371 |
| 1977 | 1,434 |
| 1978 | 1,376 |
| 1979 | 1,793 |
| 1980 | 2,889 |
| 1981 | 2,441 |
| 1982 | 2,294 |
| 1983 | 2,151 |
| 1984 | 2,076 |
| 1985 | 1,810 |
| 1986 | 1,672 |
| 1987 | 1,696 |
| 1988 | 1,649 |
| 1989 | 1,543 |
| 1990 | 1,387 |
| 1991 | 1,299 |
| 1992 | 908 |
| 1993 | 825 |
| 1994 | 601 |
| 1995 | 459 |
| 1996 | 308 |
| 1997 | 260 |
| 1998 | 143 |
| 1999 | 156 |
| 2000 | 90 |
| 2001 | 39 |
| 2002 | 78 |
| 2003 | 42 |
| 2004 | 43 |
| 2005 | 36 |
| 2006 | 6 |
| 2007 | 13 |