Year Percent 1982-01-01 0.22475200000000000 1983-01-01 0.19460100000000000 1984-01-01 0.16364500000000000 1985-01-01 0.20681400000000000 1986-01-01 0.24200600000000000 1987-01-01 0.28657800000000000 1988-01-01 0.27186500000000000 1989-01-01 0.23028700000000000 1990-01-01 0.21317700000000000 1991-01-01 0.21358000000000002 1992-01-01 0.21358000000000002 1993-01-01 0.21358000000000002 1994-01-01 0.21358000000000002 1995-01-01 0.21358000000000002 1996-01-01 0.21358000000000002 1997-01-01 0.25959600000000000 1998-01-01 0.26152400000000000 1999-01-01 0.26561799999999997 2000-01-01 0.26561799999999997 2001-01-01 0.26561799999999997 2002-01-01 1.71020000000000000 2003-01-01 1.56821000000000000 2004-01-01 1.35465000000000000 2005-01-01 1.21316000000000000 2006-01-01 1.01521000000000000 2007-01-01 2.10280000000000000 2008-01-01 1.79571000000000000 2009-01-01 2.71917999999999970 2010-01-01 3.99451999999999960 2011-01-01 5.03326000000000000 2012-01-01 5.43535000000000000 2013-01-01 5.11212000000000000 2014-01-01 6.54825000000000000 2015-01-01 8.39655000000000000 2016-01-01 10.07950000000000000