Year Number 2008-01-01 5.9062 2009-01-01 16.5906 2010-01-01 7.8035 2011-01-01 13.6866 2012-01-01 18.3629 2013-01-01 21.9387 2014-01-01 21.7100 2015-01-01 21.4658 2016-01-01 23.3510 2017-01-01 28.9046