| Year | Count |
|---|---|
| 1963 | 5 |
| 1968 | 14 |
| 1969 | 5 |
| 1970 | 5 |
| 1971 | 6 |
| 1973 | 17 |
| 1974 | 140 |
| 1975 | 126 |
| 1976 | 172 |
| 1977 | 195 |
| 1978 | 250 |
| 1979 | 325 |
| 1980 | 394 |
| 1981 | 340 |
| 1982 | 358 |
| 1983 | 427 |
| 1984 | 329 |
| 1985 | 434 |
| 1986 | 339 |
| 1987 | 389 |
| 1988 | 364 |
| 1989 | 423 |
| 1990 | 416 |
| 1991 | 618 |
| 1992 | 528 |
| 1993 | 500 |
| 1994 | 734 |
| 1995 | 653 |
| 1996 | 498 |
| 1997 | 470 |
| 1998 | 398 |
| 1999 | 268 |
| 2000 | 197 |
| 2001 | 210 |
| 2002 | 107 |
| 2003 | 118 |
| 2004 | 188 |
| 2005 | 172 |
| 2006 | 82 |
| 2007 | 81 |
| 2008 | 49 |
| 2009 | 38 |
| 2010 | 32 |
| 2011 | 10 |
| 2012 | 5 |
| 2013 | 15 |
| 2014 | 6 |