Year Percent 1987-01-01 8.0747600000000010 1988-01-01 12.9829000000000000 1989-01-01 17.4968000000000000 1990-01-01 17.4968000000000000 1991-01-01 17.4968000000000000 1992-01-01 17.4968000000000000 1993-01-01 17.4968000000000000 1994-01-01 17.4968000000000000 1995-01-01 66.4462000000000000 1996-01-01 48.5033000000000000 1997-01-01 47.3838000000000000 1998-01-01 52.3645000000000000 1999-01-01 44.3003000000000000 2000-01-01 31.3535000000000000 2001-01-01 31.7912000000000000 2002-01-01 28.0276000000000000 2003-01-01 21.3810000000000000 2004-01-01 15.7000000000000000 2005-01-01 10.4400000000000000 2006-01-01 7.3467600000000010 2007-01-01 5.8677300000000000 2008-01-01 5.0388500000000000 2009-01-01 6.3013800000000000 2010-01-01 5.7748300000000010 2011-01-01 4.4388700000000000 2012-01-01 3.4570300000000005 2013-01-01 3.0418200000000000 2014-01-01 3.3760600000000000 2015-01-01 4.6032199999999990 2016-01-01 9.8550100000000000