Year US Dollars adjusted for inflation) 1991 11254.671 1992 11079.572 1993 11491.695 1994 11069.488 1995 11904.125 1996 12751.177 1997 12712.654 1998 12955.044 1999 13241.437 2000 14321.141 2001 15323.997 2002 15787.471 2003 16330.211 2004 16930.225 2005 17481.666 2006 17567.969 2007 18860.316 2008 19068.469 2009 17960.484 2010 18028.58 2011 19308.332 2012 19841.666 2013 19161.691 2014 19216.844 2015 19414.873 2016 20654.924 2017 21233.66 2018 21543.447 2019 21880.979 2020 22227.918 2021 22607.619 2022 23027.857