Year Number 2004-01-01 30.6643 2005-01-01 30.6410 2006-01-01 31.2382 2007-01-01 31.6687 2008-01-01 31.5630 2009-01-01 31.2111 2010-01-01 30.7473 2011-01-01 30.4056 2012-01-01 30.9342 2013-01-01 30.1344 2014-01-01 29.1620 2015-01-01 28.7645 2016-01-01 27.7960