Year Number 2004-01-01 9.1238 2005-01-01 8.9841 2006-01-01 8.8364 2007-01-01 8.6899 2008-01-01 8.8206 2009-01-01 8.6737 2010-01-01 7.7315 2011-01-01 7.0858 2012-01-01 6.7190 2013-01-01 6.6191 2014-01-01 6.5238 2015-01-01 5.9382 2016-01-01 5.8632