Year US Dollars adjusted for inflation) 1991 1423.237 1992 1592.366 1993 1783.869 1994 1989.457 1995 2187.949 1996 2369.707 1997 2562.797 1998 2746.495 1999 2930.311 2000 3137.63 2001 3376.824 2002 3650.321 2003 3975.894 2004 4341.306 2005 4793.566 2006 5366.526 2007 6081.977 2008 6679.556 2009 7280.434 2010 8032.312 2011 8774.075 2012 9445.963 2013 10164.104 2014 10898.058 2015 11645.383 2016 12448.341 2017 13334.094 2018 14249.305 2019 15183.48 2020 16142.473 2021 17126.064 2022 18144.291