Year US Dollars adjusted for inflation) 1990 1298.7173 1991 1338.43938 1992 1466.23794 1993 1481.86304 1994 1572.83907 1995 1654.79807 1996 1634.74269 1997 1566.7746 1998 1551.05943 1999 1501.69195 2000 1252.89415 2001 1122.34615 2002 1062.32544 2003 1102.23683 2004 1127.07832 2005 1158.94557 2006 1209.75068 2007 1267.96836 2008 1326.86963 2009 1235.71779 2010 1290.57237 2011 1428.861 2012 1461.67126 2013 1473.76478 2014 1475.52805 2015 1482.19059 2016 1502.88704 2017 1521.2943