Year Percent 2000-01-01 2.33107211818513 2001-01-01 1.81291505092996 2002-01-01 2.46176472510964 2003-01-01 3.51760890104704 2004-01-01 4.32917046647142 2005-01-01 4.44355854794604 2006-01-01 3.53155240398761 2007-01-01 2.79898729092764 2008-01-01 2.53435663804218 2009-01-01 3.36863706956712 2010-01-01 4.39853502819819 2011-01-01 4.60145252753285 2012-01-01 5.46906685158783 2013-01-01 7.19236698830224 2014-01-01 7.13491865943433 2015-01-01 6.52561079476077 2016-01-01 5.57346753173275 2017-01-01 4.47764725311284