Year Number 2004-01-01 34.1785 2005-01-01 35.3333 2006-01-01 38.1617 2007-01-01 40.2121 2008-01-01 42.6582 2009-01-01 42.2704 2010-01-01 41.2588 2011-01-01 39.6210 2012-01-01 37.7083 2013-01-01 32.5224 2014-01-01 28.1651 2015-01-01 26.8090 2016-01-01 24.6824 2017-01-01 22.9116