1999-2008 US Mint SILVER Proof Sets 109 Coins Total 10 Complete Sets Over 14oz OF Silver Full State 25c Set. 1999-2008 Red Box US Mint Silver Proof Sets - 109 Coins Total, 10 Complete Sets. This set encompasses the entire 50 State Quarters run. The Silver Proof set became a standard product of the United States Mint in 1992, containing a dime, quarter, and half dollar composed of 90% silver. The compositions for the penny, nickel, and dollar (introduced to the set in 2000) remained the same as in the standard proof sets.