Year US Dollars adjusted for inflation) 1991 50806.164 1992 47818.5 1993 48699.883 1994 49245.746 1995 50416.84 1996 50824.707 1997 52358.367 1998 52574.117 1999 46145.488 2000 43889.824 2001 43551.609 2002 41979.32 2003 41508.105 2004 40271.824 2005 40237.305 2006 37420.105 2007 38387.215 2008 35599.926 2009 34196.754 2010 35455.617 2011 36350.746 2012 36521.23 2013 36888.301 2014 36818.488 2015 36705.707 2016 36377.672 2017 35598.762 2018 35375.172 2019 35598.676 2020 35945.055 2021 36469.602 2022 37066.355