Year Percent 1997-01-01 10.6223000000000000 1998-01-01 15.2436000000000000 1999-01-01 18.2089000000000000 2000-01-01 18.2089000000000000 2001-01-01 18.2089000000000000 2002-01-01 38.8202000000000000 2003-01-01 25.5096000000000000 2004-01-01 22.6216000000000000 2005-01-01 23.6004000000000000 2006-01-01 22.6799000000000000 2007-01-01 25.9183000000000000 2008-01-01 28.4885000000000000 2009-01-01 22.3175000000000000 2010-01-01 21.6396000000000000 2011-01-01 26.7085000000000000 2012-01-01 6.9026000000000000 2013-01-01 2.1812400000000003 2014-01-01 12.3522000000000000 2015-01-01 16.2188000000000000 2016-01-01 11.1328000000000000