Year Percent 1980-01-01 4.2734500000000000 1981-01-01 5.2572300000000000 1982-01-01 6.7880400000000000 1983-01-01 9.2974700000000000 1984-01-01 12.8076000000000000 1985-01-01 13.5098000000000000 1986-01-01 10.9729999999999990 1987-01-01 9.7290200000000000 1988-01-01 7.5528300000000000 1989-01-01 6.4919400000000005 1990-01-01 5.0201900000000000 1991-01-01 4.2651699999999995 1992-01-01 4.2029500000000000 1993-01-01 15.6876000000000000 1994-01-01 22.1192000000000000 1995-01-01 20.9508000000000000 1996-01-01 19.5339000000000000 1997-01-01 17.8581000000000000 1998-01-01 16.0701000000000000 1999-01-01 10.8646000000000000 2000-01-01 8.1992300000000000 2001-01-01 7.0795500000000000 2002-01-01 7.0969500000000000 2003-01-01 5.2478099999999990 2004-01-01 4.4637600000000000 2005-01-01 4.1979500000000000 2006-01-01 4.4274600000000000 2007-01-01 4.1720500000000000 2008-01-01 2.8373600000000000 2009-01-01 7.8303899999999995 2010-01-01 7.7316000000000000 2011-01-01 6.1549400000000000 2012-01-01 8.3946399999999990 2013-01-01 10.2990000000000010 2014-01-01 12.9149000000000000 2015-01-01 13.3409000000000000 2016-01-01 11.1392000000000000