Year	US Dollars
1975	1.38908
1977	1.34391
1979	2.63644
1980	3.92927
1981	3.90066
1982	2.60688
1983	3.83044
1984	3.69231
1985	6.01468
1986	4.69098
1987	6.8501
1988	19.95123
1989	5.37288
1990	16.67014
1991	38.37609
1992	40.47784
1993	41.07178
1994	1082.34377
1995	245.25009
1996	314.16143
1997	252.82253
1998	204.29796
1999	630.83889
2000	385.46786
2001	700.56936
2002	1132.25778
2003	1560.32477
2004	1330.43058
2005	895.52237
2006	1701.96235
2007	2494.39959
2008	3049.88771
2009	2289.65116
2010	2712.62579
2011	3649.713
2012	3410.57056
2013	2688.42341
2014	2058.50096
2015	2793.92043
2016	1983.03754
2017	2205.10189
2018	3147.43364
2019	4478.23952
2020	2293.95047
2021	2698.42525