Year Number 2004-01-01 2.2134 2005-01-01 3.4197 2006-01-01 3.9961 2007-01-01 4.9267 2008-01-01 5.3545 2009-01-01 6.2283 2010-01-01 6.9095 2011-01-01 7.3289 2012-01-01 8.3745 2013-01-01 9.3741 2014-01-01 11.4286 2015-01-01 18.7260 2016-01-01 21.7436