Year Number 2004-01-01 3.6473 2005-01-01 3.9903 2006-01-01 4.4110 2007-01-01 5.0730 2008-01-01 5.6220 2009-01-01 6.6318 2010-01-01 7.8407 2011-01-01 11.0790 2012-01-01 13.5729 2013-01-01 17.5039 2014-01-01 14.6591 2015-01-01 18.3688 2016-01-01 20.2735