Year current US$ 2000 10.38308048 2001 12.00212383 2002 18.5837326 2003 18.59137535 2004 28.63477135 2005 32.28604889 2006 34.9785614 2007 35.18187714 2008 38.15471268 2009 36.02885056 2010 36.498703 2011 38.68487549 2012 37.49700546 2013 39.97917175 2014 43.6758728 2015 35.03440857 2016 33.10380936 2017 31.06099701 2018 32.30886459 2019 31.30481529 2020 35.72977829 2021 35.63117981