Commensurate with the introduction of the Legend Obverse type in 1860, yearly production of proof Half Dimes at the Philadelphia Mint increased markedly over earlier levels.  Collecting proof coins had become more popular in the United States, particularly in large Eastern cities such as New York and Philadelphia.  The 14 proof deliveries in the Legend Obverse Seated Half Dime series are all of roughly similar rarity in today's market.  A few issues command premiums, however, due to limited original mintages for their identically dated business strike counterparts.  Examples of such issues are the 1863, 1864 and 1865.