Year Number 2007-01-01 58.9599214479458 2008-01-01 60.7013191777979 2009-01-01 66.3923664722717 2010-01-01 63.2283658449791 2011-01-01 59.0276103424812 2012-01-01 57.4237015971328 2013-01-01 55.4649237130750 2014-01-01 50.6730327218468