Year Number 2006-01-01 2.8938 2007-01-01 2.4778 2008-01-01 2.8721 2009-01-01 3.2088 2010-01-01 4.8900 2011-01-01 4.5198 2012-01-01 5.6525 2013-01-01 6.6391 2014-01-01 7.8196 2015-01-01 5.8213