Year US Dollars adjusted for inflation) 1991 4029.053 1992 3878.607 1993 3710.405 1994 3588.049 1995 3668.52 1996 3837.421 1997 3867.019 1998 3947.135 1999 3921.791 2000 3762.03 2001 3721.787 2002 3620.391 2003 3535.855 2004 3544.642 2005 3567.399 2006 3573.579 2007 3585.668 2008 3621.817 2009 3679.551 2010 3689.237 2011 3460.835 2012 3760.182 2013 4010.95 2014 4273.098 2015 4567.529 2016 4872.341 2017 5086.604 2018 5311.775 2019 5538.896 2020 5767.753 2021 5947.527 2022 6126.623