Year Number 2004-01-01 32.2234 2005-01-01 30.7155 2006-01-01 27.6223 2007-01-01 21.5905 2008-01-01 17.0447 2009-01-01 13.0135 2010-01-01 13.8387 2011-01-01 31.6989 2012-01-01 37.1837 2013-01-01 37.6604 2014-01-01 38.9441 2015-01-01 38.6651 2016-01-01 42.6025 2017-01-01 47.0920