Year	US Dollars
1960	0.54151
1961	3.85915
1962	2.31948
1963	2.3177
1964	2.86266
1965	2.77168
1966	3.68961
1967	2.02265
1968	2.39659
1969	1.47957
1970	1.42005
1971	1.2157
1972	0.93315
1973	0.62797
1974	1.22269
1975	1.21968
1976	0.83146
1977	0.59294
1978	0.76527
1979	0.73472
1980	0.67995
1981	1.8146
1982	1.3875
1983	0.8148
1984	1.14692
1985	0.6212
1986	1.05798
1987	2.05726
1988	1.50598
1989	1.57023
1990	1.15708
1991	1.27915
1992	-1.51115
1993	1.24665
1994	1.6143
1995	1.61655
1996	1.55266
1997	1.36336
1998	1.52368
1999	0.83223
2000	1.45377
2001	1.41416
2002	1.30992
2003	1.25555
2004	0.96513
2005	1.16297
2006	0.58362
2007	1.72236
2008	2.43226
2009	1.92687
2010	2.36706
2011	4.24194
2012	6.44342
2013	5.72933
2014	4.49303
2015	4.88912
2016	3.26129
2017	1.31359
2018	2.11727
2019	1.2867
2020	2.87308
2021	5.17403