Year current US$ 2000 168.05632853 2001 196.07187278 2002 210.92938588 2003 230.46978203 2004 240.57563113 2005 265.12718694 2006 277.45632728 2007 294.24354554 2008 280.25979196 2009 235.26063066 2010 234.62776845 2011 232.48255744 2012 238.90177756 2013 251.72202457 2014 251.40510201 2015 229.09200705 2016 203.91293051 2017 215.16397985 2018 224.51390341 2019 233.69545929 2020 208.73659694 2021 252.62833986