The pound Sterling

Worldwide market demand for silver is growing, while supplies of silver are quickly disappearing. New high-tech uses for silver will further strain already-tight supplies in the future. World demand for silver now exceeds annual production and has every year since 1990, depleting above-ground stockpiles of silver. The U.S. government, once the largest stockpiler of silver on the planet, dumped billions and billions of ounces of silver onto the world market over the years, resulting in depressed silver prices. Today, that government silver hoard is gone, and now the U.S. government is a buyer of silver at prevailing world silver prices.

Just shows what happens when your government spends beyond it's means.