Year	US Dollars
1966	56.32258
1967	80.46679
1968	76.05665
1969	77.70146
1970	81.93712
1971	69.05495
1972	80.79451
1973	109.85354
1974	151.83735
1975	164.92316
1976	122.67557
1977	182.66734
1978	374.96633
1979	76.53803
1980	225.34794
1981	189.00374
1982	165.63882
1983	177.9314
1984	267.1422
1985	203.11498
1986	270.87861
1987	232.8245
1988	191.98195
1989	143.96358
1990	358.66195
1991	170.4955
1992	180.02334
1993	219.9332
1994	206.21452
1995	167.65694
1996	150.59358
1997	128.25965
1998	116.5314
1999	104.46627
2000	97.35416
2001	77.59736
2002	93.901
2003	98.28735
2004	78.60719
2005	89.26884
2006	136.23048
2007	130.22483
2008	159.49965
2009	184.03002
2010	143.63593
2011	150.93759
2012	155.57002
2013	153.58841
2014	167.94276
2015	172.3115
2016	181.13659
2017	137.09429
2018	169.52359
2019	244.39616
2020	237.63571
2021	158.57165