Some insight for you ..
Following the war, the U.S. poured billions into rebuilding Europe via the Marshall Plan. Additionally, to stimulate European economic growth, the U.S. opened its markets to European goods. Consequently, massive quantities of dollars flowed to Europe.
As prosperity returned, Europeans converted those billions of dollars to gold. So great was the conversion that on August 15, 1971, President Nixon closed the “gold window” because the redemptions threatened to empty U.S. gold vaults. Much of the gold sent to Europe was old U.S. gold coin. Even before WWII, U.S. gold coins had been popular in Europe, and gold-loving Europeans hoarded them.