Year Percent 1983-01-01 0.5442690000000000 1984-01-01 1.1737700000000000 1985-01-01 2.6906900000000000 1986-01-01 3.3392900000000000 1987-01-01 3.4133400000000003 1988-01-01 2.3598700000000000 1989-01-01 1.7373400000000000 1990-01-01 1.5649600000000001 1991-01-01 2.1457100000000000 1992-01-01 2.8388100000000000 1993-01-01 3.7995400000000004 1994-01-01 4.2253200000000000 1995-01-01 4.7663199999999994 1996-01-01 6.9950300000000000 1997-01-01 8.7589899999999990 1998-01-01 14.0659000000000000 1999-01-01 10.1643000000000000 2000-01-01 8.6957500000000000 2001-01-01 8.7160600000000000 2002-01-01 8.5054000000000000 2003-01-01 8.8677700000000000 2004-01-01 9.1847600000000000 2005-01-01 8.8924500000000000 2006-01-01 9.4897100000000000 2007-01-01 9.6885800000000000 2008-01-01 10.4682000000000000 2009-01-01 13.7329000000000000 2010-01-01 12.1118000000000000 2011-01-01 12.4809000000000000 2012-01-01 13.4101000000000000 2013-01-01 13.9670000000000000 2014-01-01 13.2782000000000000 2015-01-01 12.7541000000000000 2016-01-01 12.2944000000000000