Year US Dollars adjusted for inflation) 1975 1663.01128 1976 2011.55419 1977 2087.30572 1978 2459.65061 1979 2608.03845 1980 3006.1359 1981 3036.67769 1982 3135.42177 1983 3068.65329 1984 3198.36515 1985 3176.87928 1986 3269.52178 1987 3238.76826 1988 3056.86181 1989 2534.71898 1990 2440.39463 1991 2357.23074 1992 2645.81498 1993 2622.15154 1994 2623.57206 1995 2678.07426 1996 2650.80923 1997 2672.81685 1998 2699.40995 1999 2743.02603 2000 2810.03515 2001 2906.62275 2002 3020.08985 2003 3082.05495 2004 3262.19058 2005 3417.73014 2006 3557.30269 2007 3687.23364 2008 3773.18767 2009 3786.53348 2010 3679.19027 2011 3578.76581 2012 3481.68874 2013 3401.07604 2014 3348.82685 2015 3297.89441 2016 3258.49324 2017 3238.252