Year Number 2006-01-01 17.8453 2007-01-01 17.2043 2008-01-01 17.1101 2009-01-01 16.5137 2010-01-01 15.9556 2011-01-01 10.7467 2012-01-01 9.4995 2013-01-01 10.0828 2014-01-01 8.9247 2015-01-01 8.6532 2016-01-01 8.0097