The Mint may not have produced SB Anthony Dollars since 81 (you sure that wasn't 91?). But when they released the Sacagawea Dollar, all I ever got in change from the Post Office (that was pushing the dollar coin) was the feminist dollar.
You're right! Sort of. The Susan B. were minted in only three years; 1979, 1981, and 1999. However, the vast majority of coins (I don't have my coin book here at work) were minted in 1979, with only token amounts (mainly for collectors) in 1981 and 1999.
They're still in circulation with the new gold dollar, however, and you can sometimes find both in the same roll, as the Susan B and the gold dollar are the same weight, diameter, and thickness.