"Inflation, as this term was always used everywhere and especially in this country, means increasing the quantity of money and bank notes in circulation and the quantity of bank deposits subject to check. But people today use the term `inflation' to refer to the phenomenon that is an inevitable consequence of inflation, that is the tendency of all prices and wage rates to rise. The result of this deplorable confusion is that there is no term left to signify the cause of this rise in prices and wages. There is no longer any word available to signify the phenomenon that has been, up to now, called inflation. . . . As you cannot talk about something that has no name, you cannot fight it. Those who pretend to fight inflation are in fact only fighting what is the inevitable consequence of inflation, rising prices. Their ventures are doomed to failure because they do not attack the root of the evil. They try to keep prices low while firmly committed to a policy of increasing the quantity of money that must necessarily make them soar. As long as this terminological confusion is not entirely wiped out, there cannot be any question of stopping inflation." - Ludwig von Mises

Your 60% drop claim is rather vapid considering I could pull any other arbitrary time horizon and give you a massive increase in purchasing power.