That would be nuts to calculate. I haven't seen anything like this calculated before. Specially physical cash... thats so hard to account. Considering there are billions spent "outside the system" in underground economy. I don't think it's possible to calculate, dollar is still a strong top #1 currency.
Well there are some pretty smart people on these forums that could probably derive a way to give an estimate. A start might be to take the M0 and subtract the amount of money that is thought to be stable as in savings accounts.
I really don't know, but I think someone could give me some rough numbers.