Year Number 2004-01-01 9.6768 2005-01-01 11.6961 2006-01-01 13.8239 2007-01-01 18.6014 2008-01-01 23.4987 2009-01-01 24.0059 2010-01-01 24.1304 2011-01-01 24.0938 2012-01-01 24.0173 2013-01-01 23.4091 2014-01-01 21.9419 2015-01-01 21.8514 2016-01-01 21.5096