According to the U.S. Geological Survey, the single biggest annual increase in production was around 15% in the year 1923, which translated to an increase in stockpiles around only 1.5%. Even if production were to double, the likely increase in stockpiles would only be around 3–4%. The highest annual increase in global stockpiles happened in 1940, when stockpiles rose by around 2.6%. Not once has the annual stockpile growth exceeded that number, and not once since 1942 has it exceeded 2%.
