Year US Dollars adjusted for inflation) 1990 1796.93643 1991 1601.59382 1992 949.03322 1993 886.03279 1994 956.47089 1995 1043.54314 1996 1121.88163 1997 1172.1368 1998 1267.57528 1999 1317.74192 2000 1404.32146 2001 1548.07585 2002 1761.88827 2003 2019.98487 2004 2244.22017 2005 2571.98576 2006 2933.83348 2007 3366.16219 2008 3629.1577 2009 3136.81173 2010 3218.38165 2011 3371.67283 2012 3606.48055 2013 3710.57574 2014 3827.3432 2015 3935.28877 2016 3932.55462 2017 4219.36855