Year US Dollars adjusted for inflation) 1991 24124.213 1992 22447.93 1993 20069.891 1994 19654.922 1995 18595.67 1996 18851.242 1997 19398.227 1998 19304.83 1999 19419.773 2000 18833.91 2001 18972.273 2002 19394.004 2003 19961.914 2004 21224.693 2005 21838.918 2006 22116.354 2007 22732.623 2008 23167.34 2009 23372.986 2010 23711.422 2011 24455.828 2012 24500.682 2013 24446.781 2014 24695 2015 23750.723 2016 21128.576 2017 20857.154 2018 21123.6 2019 21720.154 2020 22474.766 2021 23297.242 2022 24116.344