Year Percent 1975-01-01 38.553000000000004 1976-01-01 33.058800000000000 1977-01-01 33.816200000000000 1978-01-01 36.044100000000000 1979-01-01 34.552900000000000 1980-01-01 36.220800000000000 1981-01-01 38.025000000000000 1982-01-01 44.135000000000000 1983-01-01 43.719900000000000 1984-01-01 37.993400000000000 1985-01-01 36.655000000000000 1986-01-01 33.052600000000000 1987-01-01 34.021600000000000 1988-01-01 35.313300000000000 1989-01-01 40.892900000000000 1990-01-01 41.446999999999996 1991-01-01 42.646700000000000 1992-01-01 42.218999999999994 1993-01-01 47.080200000000000 1994-01-01 49.971100000000000 1995-01-01 50.923400000000000 1996-01-01 55.262600000000000 1997-01-01 60.242700000000000 1998-01-01 60.218800000000000 1999-01-01 61.746100000000000 2000-01-01 66.020500000000000 2001-01-01 73.265600000000000 2002-01-01 72.273100000000000 2003-01-01 65.243800000000000 2004-01-01 62.174900000000000 2005-01-01 65.813400000000000 2006-01-01 69.970600000000000 2007-01-01 78.539000000000000 2008-01-01 94.122300000000000 2009-01-01 101.945000000000000 2010-01-01 98.246000000000010 2011-01-01 95.398400000000000 2012-01-01 99.495500000000000 2013-01-01 98.791600000000000 2014-01-01 93.736900000000000 2015-01-01 80.696700000000000 2016-01-01 73.555600000000000