| Year | Count |
|---|---|
| 1968 | 22 |
| 1969 | 18 |
| 1970 | 60 |
| 1971 | 86 |
| 1972 | 366 |
| 1973 | 636 |
| 1974 | 699 |
| 1975 | 787 |
| 1976 | 783 |
| 1977 | 783 |
| 1978 | 900 |
| 1979 | 841 |
| 1980 | 846 |
| 1981 | 922 |
| 1982 | 916 |
| 1983 | 919 |
| 1984 | 814 |
| 1985 | 743 |
| 1986 | 642 |
| 1987 | 600 |
| 1988 | 580 |
| 1989 | 419 |
| 1990 | 448 |
| 1991 | 492 |
| 1992 | 341 |
| 1993 | 308 |
| 1994 | 263 |
| 1995 | 182 |
| 1996 | 203 |
| 1997 | 166 |
| 1998 | 121 |
| 1999 | 52 |
| 2000 | 18 |
| 2001 | 18 |
| 2003 | 16 |
| 2004 | 39 |
| 2005 | 14 |
| 2006 | 10 |
| 2007 | 5 |
| 2008 | 7 |
| 2011 | 6 |