Year Percent 1990-01-01 1.3351200000000000 1991-01-01 1.5707600000000000 1992-01-01 1.5624400000000000 1993-01-01 1.5606600000000000 1994-01-01 1.3003900000000000 1995-01-01 1.1636300000000000 1996-01-01 1.8873900000000001 1997-01-01 2.8941900000000000 1998-01-01 4.2185600000000000 1999-01-01 8.6464699999999990 2000-01-01 9.7755700000000000 2001-01-01 9.6565100000000000 2002-01-01 11.0830000000000000 2003-01-01 11.0295000000000000 2004-01-01 12.1079999999999990 2005-01-01 11.2302000000000000 2006-01-01 9.7932000000000000 2007-01-01 8.9712300000000000 2008-01-01 7.7450800000000010 2009-01-01 17.4273000000000000 2010-01-01 17.4355000000000000 2011-01-01 14.8038000000000000 2012-01-01 16.9122000000000000 2013-01-01 17.1709000000000000 2014-01-01 16.0526000000000000 2015-01-01 16.5040000000000000 2016-01-01 16.0551000000000000