Year US Dollars adjusted for inflation) 1991 14151.944 1992 14619.938 1993 13874.548 1994 13642.936 1995 13841.101 1996 13959.362 1997 14196.476 1998 14048.445 1999 13949.041 2000 14005.569 2001 13862.561 2002 14324.244 2003 14688.298 2004 16315.792 2005 16385.352 2006 17190.311 2007 17962.781 2008 18046.842 2009 17674.459 2010 18361.816 2011 18363.088 2012 17745.197 2013 18601.398 2014 18988.15 2015 19721.625 2016 20318.986 2017 19714.455 2018 19790.607 2019 19949.998 2020 20215.027 2021 20503.5 2022 20813.355