Year Number 2004-01-01 3.214688459 2005-01-01 3.311461360 2006-01-01 3.350349355 2007-01-01 3.393101514 2008-01-01 3.450683791 2009-01-01 3.488268876 2010-01-01 3.524681758 2011-01-01 3.587640967 2012-01-01 3.623354020 2013-01-01 3.435019388 2014-01-01 3.525431655