Year Percent 2000-01-01 3.75414206862831 2001-01-01 2.81833934628156 2002-01-01 3.13155663245317 2003-01-01 3.88963703472684 2004-01-01 4.84391946937910 2005-01-01 5.06781979411868 2006-01-01 4.36164308622097 2007-01-01 3.63743583316059 2008-01-01 3.00900781370293 2009-01-01 3.46405171909245 2010-01-01 4.51203353485646 2011-01-01 5.41283002835631 2012-01-01 6.22915076833786 2013-01-01 7.30186284986228 2014-01-01 7.74632674109966 2015-01-01 7.27414309383394 2016-01-01 6.50933654401053 2017-01-01 5.25705841410520