Year	US Dollars
1997	42318978918.88129
1998	43639588885.4321
1999	38802594660.0265
2000	43031435017.34529
2001	46115395457.1132
2002	50763499825.7701
2003	53496828288.26951
2004	59684305323.2699
2005	63990138288.38749
2006	70273120801.4183
2007	75743366851.9054
2008	85217465657.45529
2009	85187456468.7408
2010	86138675057.5596
2011	91684369507.07948
2012	91108192060.911
2013	94504600495.73109
2014	94224885770.02098
2015	93732847930.3456
2016	96456325478.59598
2017	98592264868.3699