Year Number 2004-01-01 7.6619 2005-01-01 7.7512 2006-01-01 7.8928 2007-01-01 8.1461 2008-01-01 8.4936 2009-01-01 8.5738 2010-01-01 8.6113 2011-01-01 8.7892 2012-01-01 9.0353 2013-01-01 9.3608 2014-01-01 9.6386 2015-01-01 10.0178 2016-01-01 10.3574