Year	US Dollars
1973	0.5108
1974	18.96891
1975	28.30237
1976	28.10469
1977	34.67284
1978	27.03239
1979	29.81878
1980	40.59554
1981	63.64075
1982	63.70812
1983	75.57778
1984	275.75337
1985	342.12933
1986	237.28109
1987	190.16093
1988	200.54668
1989	147.64573
1990	139.3278
1991	164.89906
1992	127.96912
1993	77.02622
1994	228.83673
1995	103.97847
1996	113.02291
1997	84.13154
1998	58.94539
1999	97.35731
2000	157.02957
2001	104.59902
2002	94.42766
2003	99.13555
2004	142.44494
2005	477.08018
2006	241.55764
2007	233.5198
2008	282.72195
2009	404.6835
2010	296.82826
2011	104.68334
2012	66.08461
2013	107.14438
2014	336.60529
2015	202.55505
2016	71.52026
2017	48.296
2018	260.50986
2019	119.61801
2020	562.49644
2021	546.82609