Year Number 2008-01-01 12.9438 2009-01-01 3.7827 2010-01-01 8.1355 2011-01-01 13.0875 2012-01-01 8.1520 2013-01-01 8.2774 2014-01-01 2.6944 2015-01-01 3.4375 2016-01-01 3.5436 2017-01-01 5.1735