Year current US$ 2000 9.03495451 2001 9.87728069 2002 10.73175951 2003 14.77905846 2004 17.51606116 2005 21.15232051 2006 32.15886501 2007 49.28891573 2008 53.65924334 2009 43.61072876 2010 46.90089518 2011 55.08590036 2012 51.83338807 2013 76.59731861 2014 62.4414667 2015 78.00809285 2016 66.68025641 2017 51.61192894 2018 23.78915719 2019 23.92625998 2020 12.36403293 2021 12.26999207