Year Percent 1990-01-01 18.330100000000000 1991-01-01 16.710100000000000 1992-01-01 13.238200000000000 1993-01-01 10.435100000000000 1994-01-01 8.399050000000000 1995-01-01 6.350340000000000 1996-01-01 4.988160000000000 1997-01-01 5.422760000000000 1998-01-01 6.785489999999999 1999-01-01 9.532340000000000 2000-01-01 11.655500000000000 2001-01-01 14.247000000000000 2002-01-01 15.444600000000000 2003-01-01 14.489800000000000 2004-01-01 14.675200000000000 2005-01-01 13.263100000000000 2006-01-01 16.140200000000000 2007-01-01 17.811300000000000 2008-01-01 15.027300000000000 2009-01-01 22.507600000000000 2010-01-01 22.500600000000000 2011-01-01 22.459000000000000 2012-01-01 27.743600000000000 2013-01-01 29.908300000000000 2014-01-01 29.057300000000000 2015-01-01 29.679300000000000 2016-01-01 27.185100000000000