Year Percent 1982-01-01 16.943300000000000 1983-01-01 17.739000000000000 1984-01-01 19.020300000000000 1985-01-01 20.571200000000000 1986-01-01 22.099000000000000 1987-01-01 37.366400000000000 1988-01-01 49.250700000000000 1989-01-01 46.322300000000000 1990-01-01 47.004900000000000 1991-01-01 44.667000000000000 1992-01-01 40.637800000000000 1993-01-01 39.912800000000000 1994-01-01 38.637300000000000 1995-01-01 34.799300000000000 1996-01-01 32.878200000000000 1997-01-01 32.279400000000000 1998-01-01 32.944700000000000 1999-01-01 33.922300000000000 2000-01-01 36.271500000000000 2001-01-01 39.853400000000000 2002-01-01 42.563400000000000 2003-01-01 48.179700000000000 2004-01-01 53.262400000000000 2005-01-01 57.351000000000006 2006-01-01 62.148000000000000 2007-01-01 69.700400000000000 2008-01-01 78.320800000000000 2009-01-01 82.647300000000000 2010-01-01 76.428300000000000 2011-01-01 75.072500000000000 2012-01-01 71.709200000000000 2013-01-01 63.708000000000000 2014-01-01 59.266100000000000 2015-01-01 56.612600000000000 2016-01-01 55.111000000000004