Year current US$ 1995 8000000 1996 8000000 1997 9000000 1998 9000000 1999 10000000 2000 10000000 2001 9000000 2002 8000000 2003 9000000 2004 9000000 2005 8000000 2006 7000000 2007 7000000 2008 7000000 2009 3000000 2010 3000000 2011 13000000 2012 18000000 2013 19000000 2014 23000000 2015 27000000 2016 33000000