Year US Dollars adjusted for inflation) 1965 11000000 1966 0 1972 11000000 1973 2000000 1980 22000000 1981 6000000 1987 0 2000 11000000 2001 0 2002 2000000 2007 6000000 2010 24000000 2011 12000000 2012 12000000 2015 46000000 2016 30000000 2021 32000000