Year US Dollars adjusted for inflation) 1991 13761.778 1992 12857.612 1993 11934.577 1994 11787.194 1995 11617.941 1996 11764.834 1997 11875.513 1998 11950.747 1999 12032.869 2000 12384.031 2001 11571.373 2002 11860.784 2003 12863.572 2004 14076.724 2005 14193.044 2006 14231.312 2007 14659.726 2008 14915.424 2009 14327.575 2010 14633.467 2011 14798.765 2012 14687.067 2013 14481.694 2014 14734.632 2015 14956.289 2016 14968.366 2017 14994.049 2018 15529.571 2019 15981.93 2020 16384.82 2021 16805.893 2022 17215.289