With the sole exception of 1908, the Philadelphia Mint struck proofs every year in the Motto Liberty Half Eagle series.  These are all rare issues, particularly in high grades, and the highest-mintage delivery of the type is just 230 specimens for the 1900.  Most earlier deliveries were produced to the extent of fewer than 50 coins, and attrition took a heavy toll as many proof Half Eagles were spent during the recession years of 1893, 1904, 1921 and (particualrly) 1929-1933.  The two most desirable deliveries in this proof gold series are the 1875, due to a limited mintage for its identically dated business strike counterpart, and the proof-only 1887.