Year	US Dollars
1976	2.22355
1977	2.16214
1978	2.10413
1979	2.05135
1980	1.41361
1981	1.37993
1982	1.34695
1983	1.09543
1984	1.13269
1985	2.69307
1986	3.30979
1987	2.31511
1988	1.84688
1989	2.87152
1990	6.03766
1991	31.61707
1992	45.07054
1993	47.07285
1994	67.93366
1995	65.73306
1996	70.07963
1997	77.0645
1998	71.42596
1999	72.70367
2000	75.71261
2001	74.13246
2002	73.58244
2003	84.86943
2004	86.48322
2005	76.2722
2006	70.66365
2007	81.39641
2008	87.5626
2009	115.033
2010	106.07137
2011	122.98019
2012	159.91196
2013	151.31699
2014	109.17304
2015	79.7167
2016	107.49764
2017	247.2812
2018	105.43961
2019	96.08561
2020	213.06575
2021	83.73006