If the economy grew at the rate of mining pre1976 and had no relationship post1976 then your hypothesis would be proven.
Ahhh! I understand what you are misunderstanding, now. You think that I said that the change in size of the pool of currency IS the change in the size of the economy itself. Here's what I said:
The total pool of currency needs to be able to grow with the economy.
The pool of currency and the economy are two separate things that can grow at two separate rates. It just creates serious economic problems when they are not aligned with each other. Homework assignment: read up on the Great Depression.