Year	US Dollars adjusted for inflation)
1968	1454.586
1969	1450.87427
1970	1465.9705
1971	1493.86185
1972	1499.37887
1973	1515.40624
1974	1703.4153
1975	1855.13144
1976	2104.66085
1977	2077.05308
1978	2356.04931
1979	2762.0985
1980	3345.99054
1981	3228.63053
1982	3248.88699
1983	2750.33915
1984	2641.82853
1985	2616.41807
1986	2676.17055
1987	2861.66912
1988	2798.98403
1989	2649.89125
1990	4079.34448
1991	1427.92119
1992	1840.4387
1993	2328.06452
1994	2345.58666
1995	2322.87383
1996	2500.00611
1997	2937.47386
1998	3839.82746
1999	4379.19934
2000	4311.28131
2001	4285.86362
2002	3880.1116
2003	2526.04314
2004	3792.14246
2005	3857.61041
2006	4143.6917
2007	4098.30663
2008	4325.66798
2009	4354.68363
2010	4502.74905
2011	4695.35722
2012	5178.42229
2013	5390.00959
2014	5253.62708
2015	5336.64829
2016	5750.61136
2017	5545.93729