Year Number 2004-01-01 27.5030 2005-01-01 27.6303 2006-01-01 28.8195 2007-01-01 31.1080 2008-01-01 34.3976 2009-01-01 34.7101 2010-01-01 33.8938 2011-01-01 34.3467 2012-01-01 35.8631 2013-01-01 34.8388 2014-01-01 34.8248 2015-01-01 32.8783 2016-01-01 32.7672