Year Number 2004-01-01 11.71823096 2005-01-01 13.88471211 2006-01-01 12.59734017 2007-01-01 10.16903652 2008-01-01 13.14828267 2009-01-01 14.55104271 2010-01-01 16.65543135 2011-01-01 18.85176830 2012-01-01 20.37655838 2013-01-01 15.97550394 2014-01-01 16.39657917