Year Number 2004-01-01 0.3158 2005-01-01 0.3158 2006-01-01 0.3158 2007-01-01 0.3599 2008-01-01 0.4262 2009-01-01 0.4703 2010-01-01 0.5322 2011-01-01 0.6823 2012-01-01 0.6956 2013-01-01 0.7751 2014-01-01 0.8192 2015-01-01 0.8325