Year US Dollars adjusted for inflation) 1991 16802.045 1992 18532.617 1993 19999.324 1994 21090.428 1995 21934.387 1996 22212.74 1997 22846.537 1998 22690.012 1999 21961.359 2000 21675.398 2001 20999.633 2002 19084.369 2003 19297.975 2004 20139.078 2005 21238.645 2006 22191.1 2007 23730.645 2008 24486.307 2009 22793.369 2010 25153.814 2011 25692.799 2012 25191.188 2013 25581.6 2014 24911.92 2015 25172.342 2016 24734.613 2017 25198.785 2018 25614.33 2019 26209.344 2020 27055.086 2021 27811.072 2022 28454.695