Issue #1 Jul 01, 1970 Issue #2 Jan 01, 1971 Issue #3 Apr 01, 1971 Issue #4 Jul 01, 1971 Issue #5 Oct 01, 1971 Issue #6 Apr 01, 1972 Issue #7 Jul 01, 1972 Issue #8 Oct 01, 1972 Issue #9 Apr 01, 1973 Issue #10 Jul 01, 1973 Issue #11 Oct 01, 1973 Issue #12 Apr 01, 1974 Issue #13 Jul 01, 1974 Issue #14 Oct 01, 1974 Issue #15 Apr 01, 1975 Issue #16 Jul 01, 1975 Issue #17 Oct 01, 1975 Issue #18 Apr 01, 1976 Issue #19 Jul 01, 1976 Issue #20 Oct 01, 1976