Year current US$ 2000 2.7187003839310067 2001 2.0461323890115053 2002 2.445551682278439 2003 2.6325393046879726 2004 3.527850756510564 2005 4.417855162093324 2006 5.976671143244905 2007 6.568149810025318 2008 7.269288626440285 2009 8.054291611131802 2010 8.487756562101557 2011 10.104895822696353 2012 10.167942092169673 2013 11.928746446856614 2014 11.837450022664228 2015 9.951781569650516 2016 9.399243241660848 2017 9.03938153807263 2018 9.436495388659825 2019 10.315932621927647 2020 9.359493997577463 2021 11.234541612117615