Year Percent 1998-01-01 40.700000000000000 1999-01-01 41.100000000000000 2000-01-01 34.900000000000000 2001-01-01 31.500000000000000 2002-01-01 28.100000000000000 2003-01-01 22.100000000000000 2004-01-01 17.500000000000000 2005-01-01 17.500000000000000 2006-01-01 17.500000000000000 2007-01-01 17.500000000000000 2008-01-01 17.500000000000000 2009-01-01 17.500000000000000 2010-01-01 17.500000000000000 2011-01-01 5.849000000000000 2012-01-01 9.728080000000000 2013-01-01 8.641850000000000 2014-01-01 9.365540000000000 2015-01-01 8.397910000000001