Year	US Dollars
1960	2.65045
1961	2.63518
1962	3.1425
1963	3.68247
1964	3.90538
1965	5.17278
1966	6.19418
1967	3.94472
1968	0.95152
1969	0.71322
1970	2.46361
1971	4.53433
1972	7.08165
1973	8.57404
1974	23.81199
1975	31.99987
1976	59.38986
1977	53.52782
1978	46.07152
1979	40.5453
1980	62.3926
1981	53.49715
1982	62.12843
1983	42.64856
1984	52.71188
1985	39.06435
1986	30.16194
1987	41.01359
1988	24.65037
1989	29.07625
1990	33.63184
1991	21.32651
1992	17.58168
1993	20.93268
1994	11.03955
1995	10.66797
1996	15.18388
1997	20.77308
1998	22.38965
1999	25.43977
2000	16.79129
2001	19.42335
2002	11.01184
2003	12.08888
2004	12.85462
2005	13.88324
2006	13.10234
2007	10.72807
2008	18.39427
2009	23.27547
2010	26.95932
2011	18.74538
2012	27.14447
2013	38.52764
2014	41.92077
2015	62.36415
2016	78.60593
2017	107.6769
2018	259.3445
2019	119.15449
2020	78.91143
2021	117.27676