The size of the economy and the size of the money supply are very hard to measure; the best we can do is estimate. As the economy grows, the amount of money mus

The size of the economy and the size of the money supply are very hard to measure; the best we can do is estimate. As the economy grows, the amount of money must be allowed to grow as well or we will have deflation. Even a small amount of deflation is widely regarded as worse than a small amount of inflation, so they try to err on on the positive side.