Year US Dollars adjusted for inflation) 1991 20857.604 1992 13817.143 1993 12145.269 1994 12888.751 1995 13333.441 1996 13921.812 1997 14147.829 1998 15313.409 1999 15975.764 2000 17407.873 2001 18395.906 2002 19266.176 2003 20850.562 2004 22486.992 2005 24556.33 2006 26046.912 2007 28039.764 2008 27220.471 2009 27002.418 2010 27479.887 2011 28647.197 2012 29242.766 2013 29559.762 2014 30336.404 2015 30814.281 2016 31473.547 2017 33131.324 2018 35326.156 2019 37195.289 2020 38938.68 2021 40703.898 2022 42576.203