Year Percent 1975-01-01 10.7032000000000000 1976-01-01 11.6885000000000000 1977-01-01 3.9792099999999997 1978-01-01 5.9079600000000000 1979-01-01 8.7276000000000000 1980-01-01 10.3314000000000000 1981-01-01 11.8718000000000000 1982-01-01 8.2045500000000000 1983-01-01 12.1041000000000000 1984-01-01 10.2426000000000000 1985-01-01 14.7790000000000020 1986-01-01 18.2827000000000000 1987-01-01 24.5108000000000000 1988-01-01 15.4994000000000000 1989-01-01 17.6227000000000000 1990-01-01 13.3894000000000000 1991-01-01 14.7898000000000000 1992-01-01 16.0616000000000000 1993-01-01 26.0143000000000000 1994-01-01 27.5918000000000000 1995-01-01 29.3216000000000000 1996-01-01 34.0378000000000000 1997-01-01 35.8964000000000000 1998-01-01 35.0788000000000000 1999-01-01 30.9947000000000000 2000-01-01 56.2394000000000000 2001-01-01 65.3357000000000000 2002-01-01 59.7025000000000000 2003-01-01 52.8241000000000000 2004-01-01 65.3149000000000000 2005-01-01 67.6260000000000000 2006-01-01 74.9344000000000000 2007-01-01 87.1266000000000000 2008-01-01 91.5560000000000000 2009-01-01 100.7270000000000000 2010-01-01 69.5459000000000000 2011-01-01 69.9739999999999900 2012-01-01 67.6495000000000000 2013-01-01 63.9220000000000000 2014-01-01 65.3493000000000000 2015-01-01 63.8045000000000000 2016-01-01 64.9114000000000000 2017-01-01 58.1335000000000000