Year Percent 2000-01-01 1.7234700000000000 2001-01-01 1.7038300000000000 2002-01-01 2.2696099999999997 2003-01-01 2.4705200000000000 2004-01-01 2.3874600000000000 2005-01-01 4.3846800000000000 2006-01-01 6.1525700000000000 2007-01-01 6.4466500000000000 2008-01-01 8.7577100000000010 2009-01-01 14.0167000000000000 2010-01-01 17.2601000000000000 2011-01-01 22.1243000000000000 2012-01-01 29.1077000000000000 2013-01-01 31.0818000000000000 2014-01-01 32.9032000000000000 2015-01-01 29.5955000000000000 2016-01-01 27.4830000000000000 2017-01-01 24.6607000000000000