Year Number 2004-01-01 0.2531 2005-01-01 0.2925 2006-01-01 0.3052 2007-01-01 0.3637 2008-01-01 0.3955 2009-01-01 0.4654 2010-01-01 0.5494 2011-01-01 0.6040 2012-01-01 0.6613 2013-01-01 0.6841 2014-01-01 0.7503 2015-01-01 0.8050 2016-01-01 0.8456 2017-01-01 0.8622