Year current US$ 2000 11.48470462 2001 11.55863846 2002 12.19123831 2003 15.77626455 2004 20.31762259 2005 20.69705104 2006 27.25202257 2007 34.22546477 2008 32.71954909 2009 37.9729649 2010 38.2534475 2011 49.55871459 2012 53.44950413 2013 58.09396627 2014 61.82370058 2015 58.27423987 2016 58.11934229 2017 58.37336427 2018 81.74650542 2019 75.94017276 2020 68.09277674 2021 69.72695263