Year US Dollars adjusted for inflation) 1991 8218.89 1992 8481.206 1993 8666.117 1994 9034.197 1995 9416.477 1996 9937.82 1997 10624.775 1998 11302.512 1999 11740.602 2000 11901.387 2001 12777.745 2002 12361.442 2003 12949.494 2004 13519.162 2005 11520.443 2006 12698.553 2007 13462.729 2008 14527.353 2009 13318.652 2010 13587.329 2011 14192.755 2012 14075.587 2013 14151.641 2014 14501.898 2015 14680.897 2016 15116.35 2017 15358.013 2018 15657.721 2019 16030.368 2020 16441.52 2021 16889.598 2022 17236.857