| Covers listed | |
| 1977: | August, |
| 1978: | September, October, |
| 1979: | February, |
| 1980: | October, |
| 1981: | April, June, December, |
| 1982: | January, 23 April, 15 July, 16 August, 15 November, 15 December, |
| 1983: | January, 15 February, May, July, |
| 1984: | 15 February, 15 July, 15 September, 15 November, 15 December, |
| 1985: | 15 June, 25 October, 27 November, 27 December, |
| 1988: | January, March, |
