Year	US Dollars adjusted for inflation)
1980	21184.98284
1981	19295.58522
1982	17290.81807
1983	17906.01635
1984	18304.5727
1985	16926.37474
1986	16571.42667
1987	17663.46571
1988	18240.56619
1989	17702.37559
1990	17934.74305
1991	19407.44365
1992	20178.46516
1993	22217.91332
1994	21623.01568
1995	21910.23988
1996	22220.68291
1997	22281.79511
1998	22634.88847
1999	22760.98699
2000	22955.09349
2001	22416.08185
2002	22038.3312
2003	22058.76333
2004	22144.47339
2005	22066.07113
2006	21796.01514
2007	21838.07457
2008	21563.65067
2009	20797.00522
2010	20722.10389
2011	20514.75639
2012	20921.19971
2013	21799.65217
2014	22390.68285
2015	22436.20753
2016	22291.40425
2017	22111.47724