Year Percent 2004-01-01 2.87 2005-01-01 2.72 2006-01-01 2.60 2007-01-01 3.90 2008-01-01 3.56 2009-01-01 3.76 2010-01-01 3.69 2011-01-01 4.12 2012-01-01 4.48 2013-01-01 4.61 2014-01-01 5.42 2015-01-01 6.78 2016-01-01 7.14