Year current international $ 2000 13.7412413882289 2001 13.9906124178375 2002 14.9071728210371 2003 14.4581228898302 2004 15.5004792676237 2005 16.8187988892217 2006 20.6021550079491 2007 23.0310185543866 2008 20.7635444722038 2009 20.2572115287222 2010 20.0452393632925 2011 16.5747915783604 2012 12.615209293798 2013 12.5372837264729 2014 16.2933777779539 2015 15.6493122641253 2016 15.3560232566766 2017 15.1363517860713 2018 14.9944891822241 2019 15.2897424401076 2020 16.4520654015318 2021 17.8795360240224