Year Percent 1983-01-01 0.201958 1984-01-01 0.201958 1985-01-01 0.201958 1986-01-01 0.201958 1987-01-01 0.201958 1988-01-01 0.201958 1989-01-01 0.201958 1990-01-01 0.201958 1991-01-01 0.201958 1992-01-01 0.144679 1993-01-01 0.144679 1994-01-01 0.144679 1995-01-01 0.144679 1996-01-01 0.144679 1997-01-01 0.144679 1998-01-01 0.144679 1999-01-01 0.144679 2000-01-01 22.940000 2001-01-01 11.430000 2002-01-01 9.020000 2003-01-01 8.020000 2004-01-01 8.210000 2005-01-01 11.490000 2006-01-01 8.000000 2007-01-01 5.660000 2008-01-01 2.470000 2009-01-01 2.720000 2010-01-01 2.300000 2011-01-01 1.580000 2012-01-01 1.870000 2013-01-01 2.100000 2014-01-01 1.870000 2015-01-01 1.780000 2016-01-01 1.680000