Year	US Dollars adjusted for inflation)
1980	190.47947
1981	195.3097
1982	177.78662
1983	146.93215
1984	135.28594
1985	135.26419
1986	131.64638
1987	151.15523
1988	163.78024
1989	173.66386
1990	172.91087
1991	176.78857
1992	161.83382
1993	169.21823
1994	172.79256
1995	170.58171
1996	209.86166
1997	226.30392
1998	246.7101
1999	259.23183
2000	256.53938
2001	281.06769
2002	296.98349
2003	307.03407
2004	321.30288
2005	339.13224
2006	361.74504
2007	377.38327
2008	391.71015
2009	404.59696
2010	419.22581
2011	436.14318
2012	454.10682
2013	472.59064
2014	493.2533
2015	510.79359
2016	514.96154
2017	518.96088