| Year | Count |
|---|---|
| 1966 | 12 |
| 1968 | 25 |
| 1969 | 116 |
| 1970 | 225 |
| 1971 | 375 |
| 1972 | 449 |
| 1973 | 473 |
| 1974 | 541 |
| 1975 | 594 |
| 1976 | 589 |
| 1977 | 667 |
| 1978 | 648 |
| 1979 | 606 |
| 1980 | 601 |
| 1981 | 588 |
| 1982 | 532 |
| 1983 | 430 |
| 1984 | 456 |
| 1985 | 490 |
| 1986 | 361 |
| 1987 | 409 |
| 1988 | 323 |
| 1989 | 313 |
| 1990 | 287 |
| 1991 | 283 |
| 1992 | 196 |
| 1993 | 107 |
| 1994 | 106 |
| 1995 | 59 |
| 1996 | 30 |
| 1997 | 44 |
| 1998 | 15 |
| 1999 | 10 |