Year current US$ 2001 22000000 2002 23000000 2003 1000000 2004 1000000 2005 2000000 2006 1000000 2007 4000000 2008 38000000 2009 16000000 2010 18000000 2011 17000000 2012 22000000 2013 21000000 2014 19000000 2015 12000000 2016 16000000 2017 13000000 2018 16000000 2019 15000000 2020 14000000