In 1971, silver was eliminated entirely from the coins and production increased, but the half dollar still saw only a minor increase in usage. A special design for the reverse of the half dollar was issued for the United States Bicentennial and was struck in 1975 and 1976. In addition to business strikes, special collector coins were struck for the Bicentennial in silver clad; silver proof sets in which the dime, quarter and half dollar were struck in 90% silver were first minted in 1992. In 2014, a special 50th anniversary edition of the Kennedy half dollar was also struck in 99.99% gold.