Year US Dollars adjusted for inflation) 1991 4490.908 1992 4416.75 1993 4069.562 1994 3981.6 1995 3775.109 1996 3519.09 1997 3384.193 1998 3275.985 1999 3238.599 2000 3148.208 2001 3135.694 2002 3144.985 2003 3174.25 2004 3224.756 2005 3255.224 2006 3336.765 2007 3427.353 2008 3542.916 2009 3630.345 2010 3668.178 2011 3739.125 2012 3819.44 2013 3909.366 2014 4041.935 2015 4201.405 2016 4407.096 2017 4638.538 2018 4884.451 2019 5144.37 2020 5368.32 2021 5607.087 2022 5856.681