Far fewer U.S. proof sets were issued in the 1950's than in succeeding decades. In fact, the 1959 proof set, with a production of 1.1 million, had the lowest mintage of the past 50 years. Later mintages soared to as high as 4 million. Manysets were broken up to obtain individual Franklin silver half dollar proofs, which were minted only as part of complete proof sets, resulting in even fewer intact sets being available today.