Year US Dollars 1992 11670 1993 12030 1994 12640 1995 13600 1996 14340 1997 14490 1998 14670 1999 15020 2000 15850 2001 17050 2002 17510 2003 18720 2004 19820 2005 20920 2006 22300 2007 24400 2008 25980 2009 25600 2010 25550 2011 26620 2012 27250 2013 28670 2014 30080 2015 31210 2016 32530 2017 34450