Year Percent 1975-01-01 60.51470000000000 1976-01-01 55.52200000000000 1977-01-01 54.11800000000000 1978-01-01 58.97560000000000 1979-01-01 66.31550000000000 1980-01-01 62.11950000000000 1981-01-01 70.03150000000000 1982-01-01 84.06700000000001 1983-01-01 88.53340000000000 1984-01-01 71.40400000000000 1985-01-01 66.21100000000000 1986-01-01 95.95470000000000 1987-01-01 118.87700000000001 1988-01-01 107.76000000000000 1989-01-01 101.24300000000000 1990-01-01 108.26799999999999 1991-01-01 125.36800000000000 1992-01-01 129.42300000000000 1993-01-01 134.92600000000002 1994-01-01 164.74000000000000 1995-01-01 172.55700000000002 1996-01-01 161.68600000000000 1997-01-01 150.96400000000000 1998-01-01 131.90100000000000 1999-01-01 150.68000000000000 2000-01-01 160.55100000000002 2001-01-01 129.62700000000000 2002-01-01 130.99900000000000 2003-01-01 148.52700000000002 2004-01-01 163.69299999999998 2005-01-01 194.05500000000000 2006-01-01 225.37400000000002 2007-01-01 252.19000000000000 2008-01-01 212.75000000000000 2009-01-01 214.84200000000000 2010-01-01 247.27200000000002 2011-01-01 208.80000000000000 2012-01-01 202.62300000000000 2013-01-01 234.76900000000000 2014-01-01 256.03700000000003 2015-01-01 242.88600000000000 2016-01-01 270.19700000000000 2017-01-01 328.08000000000000