Year US Dollars adjusted for inflation) 1975 102479.18903 1976 102319.72751 1977 107452.18038 1978 92822.3616 1979 100480.43676 1980 113682.03824 1981 110644.55156 1982 97254.06152 1983 87942.90269 1984 86936.84909 1985 79439.28663 1986 63832.13125 1987 62248.92875 1988 57136.0526 1989 60523.22813 1990 67606.91692 1991 64386.09112 1992 62821.15769 1993 60133.19296 1994 60932.27764 1995 61818.23378 1996 62294.12897 1997 64176.48416 1998 61231.22972 1999 59845.03704 2000 62833.25107 2001 60434.67398 2002 58707.00717 2003 59867.28994 2004 60042.59735 2005 56199.02927 2006 53926.5971 2007 48260.01091 2008 43658.94478 2009 37203.39799 2010 35037.89267 2011 35730.32935 2012 36376.45368 2013 37765.71684 2014 39146.11209 2015 40753.88634 2016 41449.68142 2017 41197.16878