Year Number 2004-01-01 8.0915 2005-01-01 7.8285 2006-01-01 7.9240 2007-01-01 7.9919 2008-01-01 8.0143 2009-01-01 8.3036 2010-01-01 8.3712 2011-01-01 8.3042 2012-01-01 8.2045 2013-01-01 8.2172 2014-01-01 8.5611 2015-01-01 8.6157 2016-01-01 8.5795