Year Number 2006-01-01 11.6482 2007-01-01 13.1868 2008-01-01 14.4214 2009-01-01 15.8533 2010-01-01 17.8177 2011-01-01 20.1182 2012-01-01 22.5662 2013-01-01 25.1880 2014-01-01 28.0119 2015-01-01 30.8350 2016-01-01 34.0441