Year Number 2007-01-01 5.1012 2008-01-01 5.3349 2009-01-01 5.4907 2010-01-01 5.6464 2011-01-01 5.8411 2012-01-01 5.8411 2013-01-01 6.1526 2014-01-01 6.5810 2015-01-01 6.6589 2016-01-01 7.5935