Its hard to get the old head around this one, but from what I've learned, they are all arbitrary numbers and derived from how much banks will lend on a discretionary basis based on what they have (from depositors); and what is ciculating is not real wealth, it is lent based on a small fraction of actual wealth.
From my understanding it is impossible to know real wealth as banks can lend on a discretionary basis on their own models and ratios.