Year current US$ 1995 22000000 1996 16000000 1997 9000000 1998 13000000 1999 14000000 2000 13000000 2001 15000000 2002 21000000 2003 30000000 2004 30000000 2005 34000000 2006 37000000 2007 42000000 2008 49000000 2009 47000000 2010 43000000 2011 24000000 2012 12000000 2013 13000000 2014 19000000 2015 16000000 2016 17000000 2017 18000000 2018 23000000 2019 18000000