Year Number 2009-01-01 23.6276 2010-01-01 23.9882 2011-01-01 20.5790 2012-01-01 21.2966 2013-01-01 20.8270 2014-01-01 20.6745 2015-01-01 21.7669 2016-01-01 22.9318 2017-01-01 24.1367