Just throwing a few ideas out there..
1967: Sgt. Pepper
1968: The White Album
1969: The Crimson King, Ummagumma
1972: Thick as a Brick, Foxtrot, Close to the Edge, Focus 3
1973: Selling England, Topographic Oceans, Tubular Bells
1974: The Lamb, Relayer, Red, Banquet, Eldorado
1975: Legend of King Arthur, Scheherazade, Wish You Were Here, Fish Out of Water
1976: Trick of the Tail, Moonmadness, Unorthodox Behaviour
1977: Seconds Out, Gabriel I, Going for the One, Farewell to Kings
Your vote: 1971