Year US Dollars adjusted for inflation) 1991 3445.31 1992 3771.302 1993 3779.958 1994 3996.676 1995 4186.794 1996 4102.858 1997 3891.617 1998 3824.016 1999 3669.009 2000 3001.562 2001 2658.758 2002 2500.789 2003 2596.522 2004 2653.422 2005 2727.136 2006 2847.152 2007 2987.401 2008 3129.664 2009 2894.083 2010 3028.42 2011 3362.129 2012 3437.113 2013 3453.559 2014 3415.76 2015 3458.296 2016 3473.096 2017 3516.245 2018 3557.822 2019 3611.979 2020 3675.823 2021 3747.03 2022 3824.932