The Inflation Puzzle. Martin Feldstein, May 29, 2015, Opinion. “The low rate of inflation in the United States is a puzzle, especially to economists who focus on the relationship between inflation and changes in the monetary base. After all, in the past, increases and decreases in the growth rate of the monetary base (currency in circulation plus commercial banks’ reserves held at the central bank) produced – or at least were accompanied by – rises and falls in the inflation rate. And, because the monetary base is controlled directly by the central bank, and is not created by commercial banks, many believe that it is the…” Link