Year Number 2004-01-01 0.3555 2005-01-01 0.3622 2006-01-01 0.4025 2007-01-01 0.4595 2008-01-01 0.5031 2009-01-01 0.5433 2010-01-01 0.5333 2011-01-01 0.5567 2012-01-01 0.5500 2013-01-01 0.5165 2014-01-01 0.4796 2015-01-01 0.4930 2016-01-01 0.5165