Year current US$ 2000 52.41205766 2001 55.82246722 2002 58.89033492 2003 60.2452122 2004 60.35195018 2005 59.78591929 2006 58.91585356 2007 60.7862995 2008 62.18460913 2009 58.91704387 2010 59.75211149 2011 60.42922444 2012 62.17840073 2013 66.50602 2014 67.84838015 2015 67.62557327 2016 67.29335231 2017 66.33750269 2018 67.29455068 2019 68.96304597 2020 59.56815039 2021 70.58541823