Year US Dollars adjusted for inflation) 1987 2789.78187 1988 3020.56865 1989 2817.85675 1990 3713.35617 1991 3443.98162 1992 2845.45806 1993 2808.24853 1994 2263.55635 1995 2054.28249 1996 2151.27256 1997 1876.36776 1998 1983.01544 1999 2282.97592 2000 2381.17573 2001 2458.50768 2002 2440.27735 2003 2495.28836 2004 2593.51525 2005 2900.12255 2006 3181.07379 2007 3489.33006 2008 3949.04823 2009 4129.54353 2010 4439.203 2011 5006.29623 2012 5462.98055 2013 5909.77104 2014 6399.27066 2015 6693.93561 2016 6986.85594 2017 7317.54951