Year	US Dollars
1971	0.02297
1973	0.45041
1974	1.52135
1975	1.11657
1977	1.3858
1978	3.13774
1979	2.56533
1980	2.82271
1981	3.29266
1982	2.56989
1983	2.50026
1984	2.43297
1986	0.51292
1987	0.99982
1988	0.97487
1990	2.09306
1992	0.52052
1993	34.17248
1994	75.47123
1995	68.74125
1996	69.56048
1997	53.89776
1998	72.67669
1999	63.59918
2000	74.39571
2001	115.64113
2002	88.98008
2003	119.45473
2004	95.36976
2005	123.50745
2006	43.81456
2007	54.17666
2008	48.38014
2009	46.24681
2010	51.56419
2011	41.59223
2012	41.80353
2013	24.66655
2014	25.3323
2015	28.11971
2016	19.85566
2017	23.31515
2018	24.45018
2019	76.02854
2020	17.10693
2021	11.44653