Year current US$ 1995 43000000 1996 42000000 1997 38000000 1998 58000000 1999 34000000 2000 31000000 2001 30000000 2002 26000000 2003 22000000 2004 48000000 2005 49000000 2006 49000000 2007 51000000 2008 46000000 2009 72000000 2010 61000000 2011 30000000 2012 44000000 2013 38000000 2014 54000000 2015 50000000 2016 30000000 2017 65000000 2018 41000000 2019 32000000 2020 36000000