Year current US$ 2000 145.51017011 2001 160.58202721 2002 165.64705078 2003 171.86465389 2004 194.71793593 2005 205.13186629 2006 221.01515155 2007 245.59918957 2008 264.79069291 2009 231.85561648 2010 270.81238963 2011 301.36784284 2012 312.03181574 2013 339.28454115 2014 320.35615835 2015 291.36755483 2016 252.74439283 2017 260.20140364 2018 263.35165641 2019 271.74970981 2020 284.78014217 2021 305.91035084