Year Number 2004-01-01 0.1435 2005-01-01 0.1457 2006-01-01 0.1479 2007-01-01 0.1479 2008-01-01 0.1502 2009-01-01 0.1502 2010-01-01 0.1546 2011-01-01 0.1568 2012-01-01 0.1789 2013-01-01 0.1789 2014-01-01 0.1789 2015-01-01 0.1811