Year	US Dollars
1960	1.45079
1961	2.47711
1962	2.74209
1963	3.22386
1964	3.66563
1965	3.91955
1966	4.62356
1967	4.80874
1968	3.87424
1969	2.93312
1970	3.09451
1971	3.42311
1972	2.93252
1973	4.38364
1974	4.0717
1975	5.46738
1976	6.21821
1977	4.31483
1978	4.04267
1979	7.33734
1980	4.06104
1981	4.08974
1982	4.66836
1983	5.5094
1984	7.5751
1985	8.55061
1986	10.1137
1987	19.70938
1988	15.01336
1989	13.7118
1990	13.84711
1991	18.50785
1992	20.27813
1993	16.6813
1994	16.92244
1995	16.22774
1996	20.24845
1997	13.18837
1998	14.84136
1999	12.33721
2000	12.28923
2001	13.3315
2002	17.86604
2003	15.24902
2004	13.62065
2005	18.72184
2006	15.26655
2007	16.14248
2008	17.1362
2009	15.16405
2010	11.24314
2011	11.8981
2012	9.5622
2013	9.57324
2014	10.34278
2015	19.64448
2016	14.82458
2017	12.64363
2018	23.74752
2019	29.2238
2020	19.52402
2021	16.76674