Year Number 2007-01-01 2.5100 2008-01-01 4.7878 2009-01-01 6.2677 2010-01-01 6.8810 2011-01-01 7.5073 2012-01-01 6.6054 2013-01-01 6.3744 2014-01-01 8.4409 2015-01-01 3.6452 2016-01-01 3.7859