Year Percent 2004-01-01 0.30 2005-01-01 0.36 2006-01-01 0.41 2007-01-01 0.56 2008-01-01 0.60 2009-01-01 0.72 2010-01-01 0.68 2011-01-01 0.73 2012-01-01 0.89 2013-01-01 1.01 2014-01-01 1.19 2015-01-01 1.36 2016-01-01 1.48