| Year | Count |
|---|---|
| 1964 | 5 |
| 1968 | 6 |
| 1970 | 15 |
| 1971 | 12 |
| 1972 | 13 |
| 1973 | 24 |
| 1974 | 34 |
| 1975 | 70 |
| 1976 | 60 |
| 1977 | 86 |
| 1978 | 239 |
| 1979 | 319 |
| 1980 | 363 |
| 1981 | 287 |
| 1982 | 235 |
| 1983 | 440 |
| 1984 | 493 |
| 1985 | 686 |
| 1986 | 795 |
| 1987 | 715 |
| 1988 | 692 |
| 1989 | 767 |
| 1989 | 6 |
| 1990 | 717 |
| 1991 | 748 |
| 1992 | 677 |
| 1993 | 636 |
| 1994 | 727 |
| 1995 | 537 |
| 1996 | 449 |
| 1997 | 454 |
| 1998 | 437 |
| 1999 | 351 |
| 2000 | 315 |
| 2001 | 253 |
| 2002 | 174 |
| 2003 | 157 |
| 2004 | 130 |
| 2005 | 123 |
| 2006 | 34 |
| 2007 | 66 |
| 2008 | 45 |
| 2009 | 13 |
| 2010 | 19 |
| 2011 | 5 |
| 2013 | 5 |
| 2020 | 15 |