Year	US Dollars
1960	0.70608
1961	0.94068
1962	1.17888
1963	1.06188
1964	0.6638
1965	0.84643
1966	1.00088
1967	1.06251
1968	1.58148
1969	1.40717
1970	1.40171
1971	1.61446
1972	1.58307
1973	2.15936
1974	3.71245
1975	4.09112
1976	4.22688
1977	3.41564
1978	4.06666
1979	5.48292
1980	6.04084
1981	6.83579
1982	5.3564
1983	8.84395
1984	9.16795
1985	17.83276
1986	15.22386
1987	14.54496
1988	21.68966
1989	15.75441
1990	21.07959
1991	21.86476
1992	22.351
1993	20.10014
1994	19.12218
1995	15.25805
1996	13.75792
1997	9.45414
1998	10.45734
1999	9.88497
2000	10.26079
2001	15.98982
2002	18.63909
2003	22.15643
2004	24.30644
2005	24.90153
2006	25.53047
2007	31.78867
2008	39.31204
2009	44.07509
2010	38.71857
2011	38.07415
2012	34.33823
2013	40.0223
2014	35.93059
2015	31.60759
2016	38.79044
2017	38.12226
2018	44.46131
2019	40.97989
2020	45.26571
2021	33.10126