Year Number 2006-01-01 26.9561 2007-01-01 31.8080 2008-01-01 31.9189 2009-01-01 29.2970 2010-01-01 27.4518 2011-01-01 26.7557 2012-01-01 25.8751 2013-01-01 24.6248 2014-01-01 23.9856 2015-01-01 22.2316 2016-01-01 21.7460