Year current US$ 2000 17.035927992203398 2001 18.310756116863576 2002 18.575851195810827 2003 20.101174183972834 2004 22.772678192593236 2005 24.932862342031864 2006 27.279659398594983 2007 33.15345324193316 2008 35.05192577312584 2009 35.27628356243987 2010 41.10894722401462 2011 43.98822019811061 2012 44.81510575375625 2013 51.047412857497235 2014 52.71638161133798 2015 54.23543233019825 2016 56.6604356521395 2017 55.443450511808486 2018 56.38839285767233 2019 58.50368405142013 2020 61.27246933970128 2021 70.17662494970703