Year	US Dollars
1973	1.17735
1974	35.55089
1975	57.56698
1976	42.21223
1977	37.44111
1978	41.79374
1979	53.32984
1980	90.24935
1981	84.48023
1982	69.55788
1983	47.95595
1984	35.89265
1985	49.50138
1986	111.41236
1987	119.35224
1988	151.23667
1989	136.21795
1990	136.63801
1991	141.24845
1992	160.12788
1993	120.48829
1994	110.75616
1995	417.25786
1996	230.29136
1997	51.97942
1998	180.96614
1999	144.65547
2000	55.35396
2001	71.45308
2002	40.28206
2003	55.43374
2004	93.95425
2005	70.15164
2006	43.07753
2007	594.18536
2008	238.22474
2009	262.01749
2010	154.15158
2011	163.38096
2012	76.88536
2013	79.2927
2014	92.50599
2015	126.78199
2016	86.06778
2017	112.36487
2018	172.39578
2019	805.15424
2020	727.50213
2021	1210.75029