Year US Dollars adjusted for inflation) 1990 3118.54659 1991 3049.01599 1992 2324.45298 1993 1760.55465 1994 1394.74421 1995 1216.07792 1996 1219.50935 1997 1277.85412 1998 1392.36119 1999 1482.32977 2000 1633.39444 2001 1781.2464 2002 1955.41315 2003 2158.00717 2004 2357.39603 2005 2949.44282 2006 3923.65815 2007 4851.17691 2008 5262.10136 2009 5639.00169 2010 5842.80578 2011 5770.9697 2012 5820.07985 2013 6078.32065 2014 6122.98049 2015 6117.03086 2016 5861.51196 2017 5805.13454