Year Percent 1980-01-01 0.1261920000000000 1981-01-01 0.0977730000000000 1982-01-01 0.0977730000000000 1983-01-01 0.0977730000000000 1984-01-01 0.0977730000000000 1985-01-01 0.0977730000000000 1986-01-01 0.0977730000000000 1987-01-01 0.0977730000000000 1988-01-01 0.0977730000000000 1989-01-01 0.6417830000000000 1990-01-01 0.7488140000000000 1991-01-01 0.7399840000000000 1992-01-01 0.6890180000000000 1993-01-01 5.5322600000000000 1994-01-01 5.4188199999999990 1995-01-01 5.6377000000000000 1996-01-01 6.0641600000000000 1997-01-01 6.4799200000000000 1998-01-01 6.5890100000000010 1999-01-01 5.8412700000000000 2000-01-01 4.3093100000000000 2001-01-01 3.7149699999999997 2002-01-01 3.7189500000000000 2003-01-01 3.2980400000000003 2004-01-01 4.6724400000000000 2005-01-01 7.6199800000000000 2006-01-01 16.6957000000000000 2007-01-01 22.7799000000000000 2008-01-01 20.5043000000000000 2009-01-01 33.1018000000000000 2010-01-01 29.9622000000000000 2011-01-01 28.6582000000000000 2012-01-01 29.8079000000000000 2013-01-01 31.4218000000000000 2014-01-01 30.2677000000000000 2015-01-01 36.4413000000000000 2016-01-01 43.7131000000000000