“M2 money supply includes more than just currency. It also includes demand deposits, travelers checks, savings accounts, time deposits of under $100,000, and balances in retail money market mutual funds. But this doesn’t mean cash isn’t keeping up with the Fed’s money printing. Below is a chart showing the growth of currency in circulation, since 1990.”
http://www.economicpolicyjournal.com/2012/10/inflation-at-currency-level.html
