Year	US Dollars
1960	2.32169
1961	4.21293
1962	5.99494
1963	7.24432
1964	8.96638
1965	7.76678
1966	28.20196
1967	25.34327
1968	28.49038
1969	38.17427
1970	37.11833
1971	53.4545
1972	66.46024
1973	77.75351
1974	163.27563
1975	122.34094
1976	293.61787
1977	133.76973
1978	167.40207
1979	332.22361
1980	372.21977
1981	251.30907
1982	207.11445
1983	207.97993
1984	182.71696
1985	157.82871
1986	172.98224
1987	353.89693
1988	263.08454
1989	245.00446
1990	310.10989
1991	298.23246
1992	244.67608
1993	206.33906
1994	243.45581
1995	261.41185
1996	175.94469
1997	151.33811
1998	161.12471
1999	165.92684
2000	184.77254
2001	147.43648
2002	135.01547
2003	159.27008
2004	181.71375
2005	185.17497
2006	222.45349
2007	252.33747
2008	398.20136
2009	421.33764
2010	445.9917
2011	369.64671
2012	396.17121
2013	346.59663
2014	371.98948
2015	674.87103
2016	455.93855
2017	457.20939
2018	440.43351
2019	429.03512
2020	494.15276
2021	522.28351