Year Number 2004-01-01 13.66061600 2005-01-01 16.11767265 2006-01-01 14.95425497 2007-01-01 12.72030618 2008-01-01 15.79510136 2009-01-01 17.11448289 2010-01-01 16.65543135 2011-01-01 18.85176830 2012-01-01 19.89482532 2013-01-01 21.70615240 2014-01-01 17.53373829