Year current US$ 2000 15.248990996991216 2001 16.439030717735193 2002 16.3749687888933 2003 18.367249903873176 2004 20.60965674032912 2005 23.19537587118382 2006 25.511742509234114 2007 29.860385813383946 2008 32.492461268783316 2009 32.33737039102743 2010 36.78754539054937 2011 39.403092007064664 2012 41.56515839238862 2013 46.84713378911149 2014 47.676679390178045 2015 47.9027666425804 2016 47.212662872063525 2017 44.112594929047575 2018 44.730436145847364 2019 46.21769486357775 2020 46.62959277510775 2021 53.51606807416368