Year	current US$
1978	492991781.759557
1979	632794119.069509
1980	1606539258.30398
1981	1508129277.47921
1982	1300823142.50487
1983	1082397054.76257
1984	1116421443.92491
1985	878077121.233237
1986	-225053231.581016
1987	-285357390.781694
1988	278795189.716062
1989	221730886.554554
1990	436318531.317866
1991	640614369.226076
1992	134133477.37504
1993	20703051.9331359
1994	541953343.173242
1995	779959115.870139
1996	1064966038.03759
1997	1298328901.43024
1998	330604265.214409
1999	711543898.30315
2000	1287651714.90019
2001	857842773.228882
2002	946540056.296858
2003	1038320316.37968
2004	1199336262.06273
2005	2742335904.87968
2007	3000959010.06465
2008	4461035350.88457
2009	2212297214.02543
2010	3530136302.03588
2011	4938857483.27776
2012	4641762259.82506
2013	4085686509.53437
2014	4587375003.9315
2015	2971314203.8938