Year	current US$
1977	19077777.7777778
1978	21703703.7037037
1979	23814814.8148148
1980	32122222.2222222
1981	34162962.962963
1982	29862962.962963
1983	29200000
1984	38548148.1481481
1985	43188888.8888889
1986	57844444.4444444
1987	69129629.6296296
1988	75159259.2592593
1989	79207407.4074074
1990	82385185.1851852
1991	96962962.962963
1992	112796296.296296
1993	115414814.814815
1994	120948148.148148
1995	118507407.407407
1996	127618518.518519
1997	140381121.862603
1998	145126608.089571
1999	146164683.20172
2000	150139027.916806
2001	153063804.545286
2002	153459088.718348
2003	165346086.827568
2004	193949555.555556
2005	226658074.074074
2006	235708629.62963
2007	233020481.481481
2008	235437481.481481
2009	176575629.62963
2010	212200333.333333
2011	261345000
2012	278681444.444444
2013	324851777.777778
2014	542596259.259259
2015	531193481.481481
2016	518488000