Year Percent 1978-01-01 192.38700000000000 1979-01-01 426.26199999999994 1980-01-01 251.47799999999998 1981-01-01 361.66100000000000 1982-01-01 84.22250000000000 1983-01-01 52.10990000000000 1984-01-01 62.06090000000000 1985-01-01 97.07130000000000 1986-01-01 124.21100000000000 1987-01-01 208.60700000000000 1988-01-01 71.21500000000000 1989-01-01 67.23220000000000 1990-01-01 57.64590000000000 1991-01-01 46.20480000000000 1992-01-01 36.89640000000000 1993-01-01 36.93310000000000 1994-01-01 35.91270000000000 1995-01-01 40.81210000000000 1996-01-01 46.56170000000000 1997-01-01 39.82330000000000 1998-01-01 23.98920000000000 1999-01-01 28.89720000000000 2000-01-01 31.50980000000000 2001-01-01 41.89550000000000 2002-01-01 22.41180000000000 2003-01-01 21.49990000000000 2004-01-01 30.80790000000000 2005-01-01 26.29420000000000 2006-01-01 28.06180000000000 2007-01-01 31.77990000000000 2008-01-01 27.03040000000000 2009-01-01 28.63220000000000 2010-01-01 26.77070000000000 2011-01-01 23.02130000000000 2012-01-01 26.40120000000000 2013-01-01 30.70020000000000 2014-01-01 26.00050000000000 2015-01-01 25.88400000000000 2016-01-01 32.46930000000000 2017-01-01 28.52490000000000