Year Number 2004-01-01 4.6950 2005-01-01 4.1742 2006-01-01 3.7789 2007-01-01 5.2068 2008-01-01 6.2644 2009-01-01 6.4785 2010-01-01 6.5607 2011-01-01 6.4052 2012-01-01 5.8145 2013-01-01 5.9038 2014-01-01 5.5478 2015-01-01 5.4181 2016-01-01 5.3629