Year Number 2004-01-01 22.6066 2005-01-01 22.6649 2006-01-01 22.6537 2007-01-01 21.8726 2008-01-01 21.5824 2009-01-01 21.4183 2010-01-01 19.5184 2011-01-01 19.3196 2012-01-01 18.8667 2013-01-01 18.0824 2014-01-01 17.2429 2015-01-01 15.9174 2016-01-01 13.5867