Year	US Dollars
1960	0.0455
1961	0.70697
1962	2.79766
1963	6.2838
1964	3.74519
1965	6.24695
1966	3.67394
1967	2.00463
1968	1.49975
1969	3.2399
1970	2.42754
1971	2.22192
1972	1.09556
1973	2.52407
1974	4.38558
1975	5.31168
1976	2.23451
1977	4.77763
1978	12.3415
1979	11.37313
1980	17.83169
1981	21.01856
1982	22.33533
1983	12.58549
1984	22.25437
1985	20.4134
1986	29.67003
1987	37.93482
1988	42.6556
1989	59.18354
1990	45.88815
1991	57.06396
1992	65.46652
1993	58.22798
1994	49.32863
1995	55.69104
1996	38.79416
1997	48.62928
1998	44.98817
1999	29.09272
2000	18.40118
2001	34.24813
2002	29.63351
2003	28.57076
2004	30.6672
2005	21.10586
2006	18.55395
2007	26.98311
2008	35.91286
2009	21.71969
2010	21.51454
2011	19.19885
2012	58.70591
2013	42.29053
2014	49.68692
2015	46.39602
2016	47.52835
2017	38.58166
2018	52.09296
2019	43.64809
2020	54.95052
2021	43.35383