Year US Dollars adjusted for inflation) 1991 17386.379 1992 18283.916 1993 18650.07 1994 19598.209 1995 19106.979 1996 20414.877 1997 21824.012 1998 22184.818 1999 21920.096 2000 21835.41 2001 20950.213 2002 19971.4 2003 20201.094 2004 20292.457 2005 21541.104 2006 21475.725 2007 22329.889 2008 23228.469 2009 23772.012 2010 25338.582 2011 26088.814 2012 27082.07 2013 28381.998 2014 28936.363 2015 29352.699 2016 29845.359 2017 30464.67 2018 31301.518 2019 32225.682 2020 33120.414 2021 34062.453 2022 34993.195