Year Percent 1998-01-01 27.0000000000000000 1999-01-01 33.7000000000000000 2000-01-01 33.3000000000000000 2001-01-01 13.1000000000000000 2002-01-01 13.1000000000000000 2003-01-01 34.9000000000000000 2004-01-01 29.3000000000000000 2005-01-01 29.3000000000000000 2006-01-01 29.3000000000000000 2007-01-01 10.6000000000000000 2008-01-01 8.8000000000000000 2009-01-01 8.0000000000000000 2010-01-01 6.2914900000000005 2011-01-01 4.4286699999999990 2012-01-01 4.5942300000000005 2013-01-01 5.0464199999999995 2014-01-01 5.4551200000000000 2015-01-01 5.9887600000000000 2016-01-01 11.6613000000000000