Year Percent 1998-01-01 8.1000000000000000 1999-01-01 26.0000000000000000 2000-01-01 31.0000000000000000 2001-01-01 13.4000000000000000 2002-01-01 8.4000000000000000 2003-01-01 7.9000000000000000 2004-01-01 6.4000000000000000 2005-01-01 5.5000000000000000 2006-01-01 4.1000000000000000 2007-01-01 3.7000000000000000 2008-01-01 3.4000000000000000 2009-01-01 4.1000000000000000 2010-01-01 3.3546000000000000 2011-01-01 3.1977300000000000 2012-01-01 3.7560200000000000 2013-01-01 3.5571500000000000 2014-01-01 3.5837100000000000 2015-01-01 4.4040599999999990 2016-01-01 3.9643300000000004