Year	US Dollars
1960	0.01786
1961	0.24556
1962	0.65423
1963	1.11473
1964	9.26757
1965	8.53355
1966	8.29075
1967	10.65328
1968	8.75329
1969	9.79956
1970	6.95574
1971	7.3654
1972	11.91022
1973	11.65806
1974	16.33543
1975	23.97187
1976	16.6886
1977	19.16699
1978	21.53463
1979	34.87386
1980	45.59313
1981	41.45825
1982	36.25334
1983	37.0166
1984	52.18467
1985	40.67644
1986	52.30623
1987	68.82184
1988	77.0312
1989	69.29238
1990	88.59751
1991	59.8471
1992	59.38042
1993	55.59465
1994	52.56217
1995	51.20386
1996	50.28289
1997	26.47123
1998	33.92907
1999	32.48928
2000	20.19063
2001	19.82172
2002	15.2672
2003	12.78918
2004	26.74515
2005	21.13887
2006	31.1083
2007	41.13979
2008	58.2844
2009	52.82898
2010	56.00349
2011	56.79813
2012	47.76983
2013	42.23281
2014	127.32525
2015	101.03473
2016	103.33232
2017	102.46279
2018	125.82486
2019	129.84794
2020	155.75835
2021	119.57332