Year	US Dollars
1960	0.48213
1961	2.94519
1962	2.22274
1963	3.90396
1964	4.11286
1965	4.5636
1966	6.41678
1967	4.33433
1968	3.13947
1969	3.59676
1970	3.89324
1971	2.81553
1972	4.18366
1973	3.16657
1974	2.4071
1975	4.14055
1976	4.12058
1977	6.07983
1978	7.74642
1979	8.38476
1980	18.66493
1981	25.99593
1982	40.62259
1983	53.332
1984	49.73633
1985	66.74108
1986	66.16255
1987	83.17414
1988	76.82132
1989	72.27711
1990	61.20161
1991	49.84737
1992	65.33439
1993	60.57553
1994	48.02006
1995	48.57003
1996	47.27676
1997	45.51711
1998	31.85512
1999	33.41407
2000	32.29849
2001	42.24215
2002	41.49868
2003	35.07969
2004	39.32299
2005	36.18692
2006	29.53714
2007	17.79081
2008	40.09658
2009	48.00706
2010	49.46325
2011	48.45578
2012	35.69221
2013	27.34397
2014	15.79348
2015	14.39561
2016	20.63352
2017	24.19473
2018	40.3834
2019	48.23878
2020	54.36431
2021	33.67032