Year current US$ 2001 4726000000 2002 5278000000 2003 5879000000 2004 7262000000 2005 7805000000 2006 9720000000 2007 12426000000 2008 15821000000 2009 12369000000 2010 13239000000 2011 16961000000 2012 17876000000 2013 20198000000 2014 19451000000 2015 13186000000 2016 12822000000 2017 14938000000 2018 18735000000 2019 17235000000 2020 4961000000