Year Percent 1985-01-01 99.5059 1986-01-01 99.0331 1987-01-01 99.0354 1988-01-01 99.0585 1989-01-01 99.1542 1990-01-01 99.2162 1991-01-01 99.2567 1992-01-01 99.3757 1993-01-01 99.3757 1994-01-01 98.9072 1995-01-01 99.0514 1996-01-01 99.1703 1997-01-01 99.2196 1998-01-01 99.2196 1999-01-01 99.2196 2000-01-01 99.2196 2001-01-01 99.2196 2002-01-01 99.2196 2003-01-01 99.6666 2004-01-01 99.9242 2005-01-01 99.9242 2006-01-01 99.9242 2007-01-01 99.9242 2008-01-01 99.9242 2009-01-01 99.9724 2010-01-01 99.9114 2011-01-01 99.9150 2012-01-01 99.7294 2013-01-01 99.7582 2014-01-01 99.7582 2015-01-01 99.0300 2016-01-01 97.8852