Year US Dollars adjusted for inflation) 1991 2657.585 1992 2961.059 1993 3436.723 1994 3540.815 1995 3302.384 1996 3470.255 1997 3217.905 1998 2991.265 1999 2955.432 2000 2786.197 2001 2699.193 2002 2612.653 2003 2591.966 2004 2586.483 2005 2680.823 2006 2665.122 2007 2787.481 2008 2898.298 2009 3000.878 2010 3154.024 2011 3442.886 2012 3639.448 2013 3748.298 2014 3980.473 2015 4171.826 2016 4190.753 2017 4229.147 2018 4272.061 2019 4337.786 2020 4405.87 2021 4474.626 2022 4545.707