Year	US Dollars
1973	1.27961
1974	50.54926
1975	110.37868
1976	60.35011
1977	68.61467
1978	98.09874
1979	124.36786
1980	241.30561
1981	202.3803
1982	230.77135
1983	137.26494
1984	225.47819
1985	231.71686
1986	164.57207
1987	224.26845
1988	253.98808
1989	340.97893
1990	282.6672
1991	254.98618
1992	183.75969
1993	128.81493
1994	283.10067
1995	361.26646
1996	623.57229
1997	210.76708
1998	280.687
1999	144.5457
2000	223.56831
2001	288.90879
2002	433.6234
2003	160.2817
2004	428.73392
2005	307.39436
2006	285.99691
2007	282.80626
2008	310.83713
2009	522.62783
2010	471.96569
2011	355.53229
2012	372.77901
2013	291.77989
2014	234.82436
2015	167.26899
2016	122.29753
2017	272.99972
2018	380.38491
2019	719.46575
2020	892.28416
2021	1091.94608