Year Number 2004-01-01 1.9664 2005-01-01 2.2893 2006-01-01 2.6587 2007-01-01 2.9857 2008-01-01 3.5609 2009-01-01 4.4611 2010-01-01 7.5906 2011-01-01 8.0766 2012-01-01 9.2723 2013-01-01 20.5844 2014-01-01 23.3052 2015-01-01 25.5051 2016-01-01 26.7612 2017-01-01 26.4975