Year Percent 2005-01-01 3.89272479033958 2006-01-01 3.24469622017850 2007-01-01 2.98505843364671 2008-01-01 3.35005708260347 2009-01-01 4.17832770157209 2010-01-01 3.69838299030002 2011-01-01 3.32354448483102 2012-01-01 3.00416065117634 2013-01-01 2.78364135132491 2014-01-01 3.02493952472598 2015-01-01 2.94723470363175 2016-01-01 3.08121815839162 2017-01-01 3.19463712850529