Year	US Dollars
1973	3.38869
1974	54.68788
1975	7.69606
1976	1.52174
1977	3.09532
1978	2.1782
1979	9.60117
1980	32.67152
1981	34.45024
1982	44.21345
1983	33.02212
1984	41.81623
1985	45.21921
1986	51.34969
1987	128.33649
1988	111.0089
1989	125.37354
1990	129.37414
1991	128.69922
1992	123.31101
1993	101.22329
1994	55.05637
1995	59.56415
1996	52.90324
1997	39.45043
1998	35.18946
1999	30.89939
2000	31.05214
2001	18.40755
2002	26.72006
2003	26.50437
2004	35.2754
2005	44.09489
2006	28.94795
2007	33.05179
2008	32.24215
2009	30.44977
2010	77.72328
2011	21.44877
2012	12.10587
2013	3.72204
2014	0.40149
2015	5.56062
2016	4.94665
2017	4.77702
2018	4.47376
2019	40.40486
2020	3.72796
2021	7.81907