Year Percent 2001-01-01 30.500000000000000 2002-01-01 28.300000000000000 2003-01-01 26.500000000000000 2004-01-01 22.000000000000000 2005-01-01 18.800000000000000 2006-01-01 21.200000000000000 2007-01-01 20.400000000000000 2008-01-01 17.100000000000000 2009-01-01 18.300000000000000 2010-01-01 16.921700000000000 2011-01-01 16.597100000000000 2012-01-01 16.650000000000000 2013-01-01 16.752000000000000 2014-01-01 17.397000000000002 2015-01-01 13.958600000000000 2016-01-01 13.195100000000000