As is true of most United States coinage of the 20th Century, these dimes were minted in fairly large numbers. There are no truly rare date/mint combinations, even in mint state, though there exists a wide span of relative rarity from one issue to the next. Scare dates within the Mercury series include 1916-D, 1921 and 1921-D, though all are obtainable for a price, and the popularity of this series with date and mint collectors is very high. A number of minor doubled-die and repunched mintmark varieties are known for this series, with most commanding only slight premiums. Various mintmark styles were used, particularly for San Francisco Mint issues, and these are just becoming popular. By far the most highly sought varieties are the 1942/41 overdated dimes of both the Philadelphia and Denver Mints. Other notable varieties include doubled-die obverses for 1929-S and 1936 and a distinctive repunched mintmark for 1941-S.