Year Percent 2001-01-01 4.19 2002-01-01 3.87 2003-01-01 3.76 2004-01-01 3.50 2005-01-01 3.52 2006-01-01 3.64 2007-01-01 3.59 2008-01-01 3.02 2009-01-01 3.40 2010-01-01 3.31 2011-01-01 3.32 2012-01-01 3.44 2013-01-01 3.33 2014-01-01 3.51 2015-01-01 3.56 2016-01-01 3.53