Year Percent 2000-01-01 2.55 2001-01-01 3.64 2002-01-01 4.44 2003-01-01 5.22 2004-01-01 5.50 2005-01-01 6.22 2006-01-01 6.87 2007-01-01 7.29 2008-01-01 7.65 2009-01-01 9.52 2010-01-01 10.43 2011-01-01 10.76 2012-01-01 12.18 2013-01-01 12.72 2014-01-01 13.75 2015-01-01 13.91 2016-01-01 14.09