Year Number 2004-01-01 27.3483 2005-01-01 27.6483 2006-01-01 27.9697 2007-01-01 28.1176 2008-01-01 28.4701 2009-01-01 28.5249 2010-01-01 29.3595 2011-01-01 28.3496 2012-01-01 30.5868 2013-01-01 30.6288 2014-01-01 30.5539 2015-01-01 30.7402 2016-01-01 30.9283