Year Percent 2001-01-01 2.35333333333333 2002-01-01 2.58250000000000 2003-01-01 2.93083333333333 2004-01-01 3.26000000000000 2005-01-01 3.35973342471837 2006-01-01 3.37642344393645 2007-01-01 3.42331236188742 2008-01-01 3.80423372380499 2009-01-01 5.37803625645144 2010-01-01 5.40020158440602 2011-01-01 5.21858965122549 2012-01-01 4.92588017722187 2013-01-01 4.91528847152051 2014-01-01 4.80497129193933 2015-01-01 4.25090625985616 2016-01-01 3.84937874482618 2017-01-01 3.32364833358208