Year US Dollars 1997 17760 1998 19740 1999 22510 2000 23200 2001 23680 2002 24750 2003 28660 2004 35230 2005 40840 2006 45600 2007 64530 2008 73290 2009 75560 2010 78300 2011 81360 2012 85910 2013 88840 2014 89970 2015 82650