Year Percent 1982-01-01 9.515989999999999 1983-01-01 9.475150000000000 1984-01-01 11.317100000000000 1985-01-01 9.894720000000000 1986-01-01 7.333390000000000 1987-01-01 7.985939999999999 1988-01-01 9.839630000000000 1989-01-01 10.689800000000000 1990-01-01 11.405600000000000 1991-01-01 12.762100000000000 1992-01-01 13.200200000000000 1993-01-01 11.964300000000000 1994-01-01 11.091000000000000 1995-01-01 10.716000000000000 1996-01-01 8.059300000000000 1997-01-01 8.444550000000000 1998-01-01 8.319780000000000 1999-01-01 8.906230000000000 2000-01-01 8.715480000000000 2001-01-01 7.743650000000000 2002-01-01 7.050389999999999 2003-01-01 7.782280000000000 2004-01-01 8.108450000000000 2005-01-01 7.957630000000000 2006-01-01 8.707210000000000 2007-01-01 9.363840000000000 2008-01-01 10.921000000000000 2009-01-01 13.805100000000000 2010-01-01 17.088500000000000 2011-01-01 17.916400000000000 2012-01-01 19.451400000000000 2013-01-01 20.392400000000000 2014-01-01 24.244300000000000 2015-01-01 25.553600000000000 2016-01-01 28.788400000000000