Year Percent 1980-01-01 5.982120000000000 1981-01-01 6.122470000000000 1982-01-01 6.797650000000000 1983-01-01 10.100000000000000 1984-01-01 9.577430000000000 1985-01-01 12.276700000000000 1986-01-01 11.283300000000000 1987-01-01 9.354330000000001 1988-01-01 8.294870000000000 1989-01-01 10.944600000000000 1990-01-01 10.452700000000000 1991-01-01 9.591500000000000 1992-01-01 10.536800000000000 1993-01-01 16.747500000000000 1994-01-01 21.353500000000000 1995-01-01 22.003800000000000 1996-01-01 22.076300000000000 1997-01-01 19.222300000000000 1998-01-01 16.464400000000000 1999-01-01 14.909100000000000 2000-01-01 15.849100000000000 2001-01-01 20.432300000000000 2002-01-01 22.518500000000000 2003-01-01 19.010500000000000 2004-01-01 15.923800000000000 2005-01-01 8.394500000000000 2006-01-01 14.683000000000000 2007-01-01 11.564700000000000 2008-01-01 11.483300000000000 2009-01-01 15.310900000000000 2010-01-01 18.335300000000000 2011-01-01 20.599800000000000 2012-01-01 26.241100000000000 2013-01-01 24.207400000000000 2014-01-01 25.802400000000000 2015-01-01 19.551400000000000 2016-01-01 10.950600000000000