The 1986-S Prof Silver is the first year of issue for the series. It proved to be extremely popular and the Mint sold over 1.446 million examples. The original issue price for each coin was set at $21 each.
This remained the highest mintage Proof Silver Eagle for the series until 2006. However, in 2006 the Mint produced a Reverse Proof besides the regular Proof Silver Eagle for the year. Only if you include the mintages of the Reverse Proofs would the overall 2006 Proof Silver Eagles have a higher mintage than the 1986. However, as a regular issue proof the 1986 Silver Eagle has the highest mintage.
Decades after the 1986-S Proof Silver Eagle was produced, examples still remain extremely popular with collectors. And for many years the coins have sold at significant premiums over their original issue prices, even for raw examples.