Year Number 2004-01-01 6.8923 2005-01-01 7.2516 2006-01-01 7.2891 2007-01-01 7.6716 2008-01-01 7.5615 2010-01-01 10.4205 2011-01-01 12.6436 2012-01-01 12.4369 2013-01-01 12.1084 2015-01-01 11.7461