| Year | Count |
|---|---|
| 1952 | 5 |
| 1957 | 6 |
| 1959 | 6 |
| 1961 | 16 |
| 1967 | 27 |
| 1968 | 39 |
| 1969 | 175 |
| 1970 | 266 |
| 1971 | 344 |
| 1972 | 275 |
| 1973 | 387 |
| 1974 | 402 |
| 1975 | 494 |
| 1976 | 505 |
| 1977 | 505 |
| 1978 | 377 |
| 1979 | 272 |
| 1980 | 173 |
| 1981 | 140 |
| 1982 | 52 |
| 1983 | 66 |
| 1984 | 13 |
| 1985 | 33 |
| 1986 | 54 |
| 1987 | 93 |
| 1988 | 57 |
| 1989 | 34 |
| 1990 | 59 |
| 1991 | 31 |
| 1992 | 17 |