Year Number 2004-01-01 13.1297 2005-01-01 12.0811 2006-01-01 12.0126 2007-01-01 12.3147 2008-01-01 11.6997 2009-01-01 11.0188 2010-01-01 10.9585 2011-01-01 10.7245 2012-01-01 9.9228 2013-01-01 8.9343 2014-01-01 8.5062 2015-01-01 7.7291 2016-01-01 6.1627