Year Number 2008-01-01 31.3515 2009-01-01 32.0277 2010-01-01 32.7985 2011-01-01 33.9018 2012-01-01 34.5688 2013-01-01 34.7104 2014-01-01 35.1563 2015-01-01 35.8333 2016-01-01 38.8709