Year Number 2004-01-01 12.7813 2005-01-01 13.7074 2006-01-01 14.5564 2007-01-01 15.4022 2008-01-01 15.4940 2009-01-01 15.8474 2010-01-01 15.6806 2011-01-01 15.7936 2012-01-01 14.5560 2013-01-01 14.9893 2014-01-01 14.8439 2015-01-01 14.3556 2016-01-01 14.2705 2017-01-01 14.5203