Year Percent 1980-01-01 1.4390700000000000 1981-01-01 1.5694100000000000 1982-01-01 2.0221000000000000 1983-01-01 2.5252200000000000 1984-01-01 3.0676400000000004 1985-01-01 4.5450900000000000 1986-01-01 4.8384800000000010 1987-01-01 6.0516900000000000 1988-01-01 5.9570099999999995 1989-01-01 8.6179200000000000 1990-01-01 10.0320000000000000 1991-01-01 10.0470000000000000 1992-01-01 9.0961800000000000 1993-01-01 7.4952500000000000 1994-01-01 7.0677100000000010 1995-01-01 6.3210800000000000 1996-01-01 6.9342600000000010 1997-01-01 7.0711500000000000 1998-01-01 7.7090800000000000 1999-01-01 7.2508000000000000 2000-01-01 5.7490800000000000 2001-01-01 5.8081000000000000 2002-01-01 5.9540400000000000 2003-01-01 5.9814300000000005 2004-01-01 6.0159900000000000 2005-01-01 5.5715699999999995 2006-01-01 6.7910000000000000 2007-01-01 7.6465100000000000 2008-01-01 7.5839399999999990 2009-01-01 7.1506399999999990 2010-01-01 6.6366700000000000 2011-01-01 5.9084100000000000 2012-01-01 6.0427000000000000 2013-01-01 7.5863900000000000 2014-01-01 8.4653500000000000 2015-01-01 9.9400600000000000 2016-01-01 9.4256600000000000