when the lp was introduced in 1948, the 78 was the conventional format for phonograph records. by 1952, 78s still accounted for slightly more than half of the units sold in the united states, and just under half of the dollar sales. the 45, oriented toward the single song, accounted for just over 30% of unit sales and just over 25% of dollar sales. the lp represented not quite 17% of unit sales and just over 26% of dollar sales.