Year current US$ 2000 19.38640241 2001 24.27204673 2002 28.89161743 2003 29.04908708 2004 28.99624196 2005 31.6173964 2006 30.2307005 2007 34.27390772 2008 38.37626312 2009 39.44803517 2010 39.72728856 2011 33.83530894 2012 28.59260808