Year	US Dollars
1960	3.98854
1961	3.40943
1962	5.10317
1963	0.53714
1964	0.90335
1965	0.60911
1966	3.66113
1967	1.01515
1968	0.88284
1969	1.79829
1970	3.45613
1971	3.31573
1972	8.05934
1973	60.79867
1974	106.48869
1975	110.37296
1976	102.533
1977	128.69344
1978	110.69507
1979	238.91877
1980	214.9511
1981	196.73205
1982	121.53716
1983	90.58751
1984	63.23984
1985	57.86778
1986	66.65891
1987	70.21829
1988	16.30071
1989	10.35558
1990	71.14355
1991	41.89315
1992	14.95393
1993	19.10164
1994	53.43963
1995	24.86962
1996	14.68433
1997	13.1164
1998	10.06545
1999	14.4247
2000	9.79663
2001	9.18702
2002	3.65998
2003	6.72237
2004	5.88973
2005	3.82596
2006	1.02511
2007	4.06704
2008	7.34561
2009	9.32872
2010	5.86725
2011	14.76063
2012	73.94635
2013	169.23894
2014	207.96442
2015	256.20539
2016	469.29085
2017	549.3149
2018	517.08481
2019	503.98664
2020	483.27759
2021	454.41913