Year Number 2007-01-01 3.2493 2008-01-01 5.5157 2009-01-01 7.1863 2010-01-01 8.3731 2011-01-01 8.8670 2012-01-01 7.9998 2013-01-01 6.4652 2014-01-01 9.4357 2015-01-01 3.7114 2016-01-01 3.7859