Year US Dollars adjusted for inflation) 1991 18107.188 1992 18388.076 1993 17797.633 1994 17173.914 1995 17192.77 1996 17722.824 1997 17367.244 1998 17071.365 1999 16768.633 2000 17033.098 2001 16758.939 2002 16957.219 2003 17184.684 2004 16799.174 2005 16979.047 2006 17747.576 2007 19244.646 2008 20001.75 2009 20236.053 2010 21959.168 2011 22381.621 2012 20802.609 2013 19935.352 2014 20781.838 2015 19808.105 2016 21789.234 2017 22323.754 2018 23091.756 2019 23927.211 2020 24814.07 2021 25833.174 2022 26907.816