Year Percent 1990-01-01 28.950 1991-01-01 29.700 1992-01-01 29.420 1993-01-01 35.500 1994-01-01 39.090 1995-01-01 39.750 1996-01-01 36.490 1997-01-01 6.770 1998-01-01 6.890 1999-01-01 6.390 2000-01-01 4.840 2001-01-01 7.460 2002-01-01 7.690 2003-01-01 8.620 2004-01-01 8.300 2005-01-01 8.795 2006-01-01 10.000 2007-01-01 9.370 2008-01-01 8.650 2009-01-01 9.825 2010-01-01 10.695 2011-01-01 8.770 2012-01-01 10.485 2013-01-01 10.810 2014-01-01 11.375 2015-01-01 10.465