Year	US Dollars
1960	4.64887
1961	5.08503
1962	3.92332
1963	3.96907
1964	4.59192
1965	4.43837
1966	5.87441
1967	5.08337
1968	4.94043
1969	6.84094
1970	9.15834
1971	5.94342
1972	4.23328
1973	10.3476
1974	10.96702
1975	9.51544
1976	8.99081
1977	7.79615
1978	9.20556
1979	25.77535
1980	55.5443
1981	28.17234
1982	27.72411
1983	26.19253
1984	28.48822
1985	26.78955
1986	37.98789
1987	36.78837
1988	54.69231
1989	58.63981
1990	77.95034
1991	184.64679
1992	138.25531
1993	70.01364
1994	116.43453
1995	120.51643
1996	183.55948
1997	72.33716
1998	101.41818
1999	118.36721
2000	97.97155
2001	158.88841
2002	79.11191
2003	138.51802
2004	205.13633
2005	120.3279
2006	112.81579
2007	130.14821
2008	116.43105
2009	114.61989
2010	87.29222
2011	90.29453
2012	88.26972
2013	81.02129
2014	69.60744
2015	72.7019
2016	67.45409
2017	86.81232
2018	53.84167
2019	58.23746
2020	68.11977
2021	109.97965