Year Number 2004-01-01 0.0847 2005-01-01 0.0941 2006-01-01 0.1695 2007-01-01 0.1869 2008-01-01 0.2488 2009-01-01 0.2636 2010-01-01 0.2676 2011-01-01 0.2744 2012-01-01 0.2771 2013-01-01 0.2784 2014-01-01 0.2717 2015-01-01 0.2676 2016-01-01 0.2676