Year US Dollars adjusted for inflation) 1991 458.748 1992 404.833 1993 443.09 1994 441.288 1995 454.05 1996 497.85 1997 500 1998 470.939 1999 484.518 2000 491.382 2001 509.824 2002 494.948 2003 463.363 2004 504.823 2005 540.598 2006 581.175 2007 628.177 2008 674.326 2009 710.138 2010 773.23 2011 830.599 2012 871.415 2013 931.039 2014 994.179 2015 1063.184 2016 1108.899 2017 1169.756 2018 1226.969 2019 1283.752 2020 1333.255 2021 1383.418 2022 1436.326