Year Number 2008-01-01 22.0578 2009-01-01 20.9724 2010-01-01 21.7979 2011-01-01 23.7753 2012-01-01 31.4245 2013-01-01 27.4444 2014-01-01 27.8767 2015-01-01 30.1210 2016-01-01 33.9497