Year Number 2007-01-01 7.0662 2008-01-01 7.7639 2009-01-01 8.3389 2010-01-01 10.3614 2011-01-01 9.8143 2012-01-01 11.0689 2013-01-01 12.3290 2014-01-01 13.0005 2015-01-01 13.3547 2016-01-01 13.7242 2017-01-01 14.1586