The possibilities of the LP format that were explored in the 1960s flowered more fully in the Seventies, with rock, R&B and countless emerging new styles reaching experimental new extremes. Nevertheless, the art of the hook still ruled the singles charts, with AM Gold balladeers and insurgent disco divas heating up the Hot 100 every summer. These are the decade’s biggest pop hits from the summer solstice to the autumn equinox, minus some of the ballads and wimpier fare from guys like Gilbert O’Sullivan and Donny Osmond.