Actually, central banks in both the US and Europe have very little control over the money supply.

The money created by central banks only accounts for about 3% of the monetary base, the remaining 97% of money that circulates in the economy is created by private banks, lending money out of thin air. Therefore money supply is actually dictated by how confident private banks are to lend to the public. A central bank can try to incentivize lending by lowering interest rates, but in the end it's private banks who choose whether to lend or not (in Europe it didn't work so well..).

It's still a pretty fucked up system either way. I think more people should work on the issue of money supply, it's probably the single most important problem in any economy.