Year Percent 1998-01-01 19.954300000000000 1999-01-01 20.485300000000000 2000-01-01 16.200000000000000 2001-01-01 13.700000000000000 2002-01-01 13.684400000000000 2003-01-01 15.632200000000000 2004-01-01 15.699000000000002 2005-01-01 18.345400000000000 2006-01-01 19.389700000000000 2007-01-01 22.533100000000000 2008-01-01 18.754200000000000 2009-01-01 22.688400000000000 2010-01-01 22.310200000000000 2011-01-01 12.003200000000000 2012-01-01 15.381400000000000 2013-01-01 7.814630000000000 2014-01-01 9.617100000000000 2015-01-01 8.950439999999999 2016-01-01 9.052430000000001