Year Number 2008-01-01 1.9669 2009-01-01 2.2244 2010-01-01 2.1736 2011-01-01 2.1680 2012-01-01 2.2931 2013-01-01 2.4324 2014-01-01 2.3645 2015-01-01 2.8244 2016-01-01 2.8843 2017-01-01 2.9670