Year	US Dollars
1960	7.45791
1961	6.91201
1962	4.81182
1963	4.1491
1964	1.45781
1965	3.80369
1966	3.92423
1967	3.93972
1968	8.42067
1969	3.9719
1970	8.38865
1971	2.48553
1972	5.9937
1973	4.52557
1974	52.86986
1975	5.31285
1976	12.7507
1977	39.28717
1978	73.17636
1979	42.54756
1980	100.49256
1981	150.29622
1982	60.91267
1983	40.52153
1984	24.39658
1985	25.53963
1986	18.84214
1987	29.8301
1988	41.702
1989	33.41652
1990	79.49467
1991	34.15574
1992	29.41469
1993	36.75766
1994	58.64752
1995	48.30995
1996	58.31577
1997	63.59994
1998	81.562
1999	45.76684
2000	46.56484
2001	45.33172
2002	45.88157
2003	118.68211
2004	58.29111
2005	49.69154
2006	173.53042
2007	203.54465
2008	218.58522
2009	117.16102
2010	89.09284
2011	94.2487
2012	137.41478
2013	109.45876
2014	130.84241
2015	150.90155
2016	180.44555
2017	213.28962
2018	239.00832
2019	213.85158
2020	251.00817
2021	249.96463