Year Percent 1982-01-01 3.8916699999999995 1983-01-01 4.5175000000000000 1984-01-01 4.0541700000000000 1985-01-01 4.0450000000000000 1986-01-01 5.7958300000000005 1987-01-01 15.3608000000000000 1988-01-01 22.4983000000000000 1989-01-01 22.3242000000000000 1990-01-01 23.0850000000000000 1991-01-01 21.2467000000000000 1992-01-01 23.1208000000000000 1993-01-01 12.9683000000000000 1994-01-01 9.0833300000000000 1995-01-01 8.3908300000000010 1996-01-01 9.6666700000000000 1997-01-01 6.9208300000000005 1998-01-01 6.9208300000000005 1999-01-01 6.9816699999999990 2000-01-01 6.9408300000000000 2001-01-01 6.3358300000000005 2002-01-01 5.5483300000000000 2003-01-01 4.7383300000000000 2004-01-01 3.4350000000000000 2005-01-01 2.4908300000000000 2006-01-01 2.2766700000000000 2007-01-01 2.2816700000000000 2008-01-01 2.2600000000000000 2009-01-01 2.2508300000000000 2010-01-01 2.1391700000000000 2011-01-01 1.6433300000000000 2012-01-01 1.4766700000000001 2013-01-01 1.5200000000000000 2014-01-01 1.3608300000000000 2015-01-01 1.1133300000000000 2016-01-01 2.4225000000000000