Year US Dollars adjusted for inflation) 1991 41666.832 1992 39249.828 1993 36915.574 1994 36578.902 1995 35229.27 1996 35049.172 1997 36220.793 1998 34224.785 1999 33745.031 2000 33764.816 2001 32201.27 2002 30830.707 2003 33349.523 2004 33769.992 2005 36326.359 2006 37636.133 2007 38907.238 2008 39029.219 2009 38036.816 2010 39104.023 2011 15279.059 2012 33110.543 2013 15930.68 2014 12161.084 2015 10897.8 2016 10546.195 2017 15478.388 2018 17314.77 2019 19211.432 2020 20605.143 2021 21952.947 2022 23300.123