| Covers listed | |
| 1967: | February, November, |
| 1968: | December, |
| 1969: | April, |
| 1970: | March, |
| 1972: | April, |
| 1973: | July, October, |
| 1974: | April, May, October, |
| 1975: | March, April, |
| 1976: | March, November, |
| 1977: | January, October, November, |
| 1978: | April, November, |
| 1979: | September, |
| 1981: | September, |
| 1982: | August, September, |
| 1983: | June/July, September, November, |
| 1984: | March, June/July, December, |
| 1985: | May, |
