Year US Dollars adjusted for inflation) 1991 12752.918 1992 13487.944 1993 14315.611 1994 15213.732 1995 16270.586 1996 17274.385 1997 17973.068 1998 16176.49 1999 16693.797 2000 17574.311 2001 17286.844 2002 17732.221 2003 18284.615 2004 18993.566 2005 19464.848 2006 20057.242 2007 21464.926 2008 21860.512 2009 20759.504 2010 21571.959 2011 21665.629 2012 21877.668 2013 21825.789 2014 22417.953 2015 22964.426 2016 23555.629 2017 24524.607 2018 25372.957 2019 26106.545 2020 26767.229 2021 27433.879 2022 28120.969