Year Number 2005-01-01 0.4533 2006-01-01 0.4765 2007-01-01 0.5164 2008-01-01 0.5561 2009-01-01 0.5829 2010-01-01 0.6107 2011-01-01 0.6422 2012-01-01 0.6726 2013-01-01 0.7023 2014-01-01 0.7368 2015-01-01 0.7644 2016-01-01 0.7652 2017-01-01 0.8193