Year US Dollars adjusted for inflation) 1991 33208.965 1992 30688.729 1993 31122.246 1994 30705.617 1995 29555.941 1996 29091.336 1997 30266.469 1998 30487.354 1999 29891.672 2000 30730.062 2001 29924.477 2002 30107.752 2003 30802.596 2004 30353.068 2005 31176.051 2006 32718.688 2007 32740.133 2008 33011.082 2009 32323.99 2010 32703.398 2011 32982.625 2012 33633.184 2013 33135.055 2014 34346.68 2015 33983.855 2016 33410.41 2017 34467.242 2018 34916.613 2019 35445.418 2020 36066.082 2021 36773.395 2022 37547.5