Year current US$ 1995 23000000 1996 26000000 1997 27000000 1998 29000000 1999 30000000 2000 31000000 2001 32000000 2002 33000000 2003 35000000 2004 38000000 2005 40000000 2006 45000000 2007 52000000 2008 58000000 2009 54000000 2010 51000000 2011 49000000 2012 49000000 2013 50000000 2014 66000000 2015 70000000 2016 77000000 2017 82000000 2018 86000000 2019 92000000 2020 27000000