Year Percent 1964-01-01 83.18750000000000 1965-01-01 83.40190000000000 1966-01-01 86.00210000000000 1967-01-01 88.87700000000001 1968-01-01 79.84670000000000 1969-01-01 78.82480000000000 1970-01-01 82.13110000000000 1971-01-01 88.36820000000000 1972-01-01 91.58050000000000 1973-01-01 99.36580000000000 1974-01-01 99.36580000000000 1975-01-01 99.36580000000000 1976-01-01 266.41600000000000 1977-01-01 155.71700000000000 1978-01-01 179.32200000000000 1979-01-01 175.23500000000000 1980-01-01 181.03000000000000 1981-01-01 206.02200000000002 1982-01-01 353.02000000000000 1983-01-01 353.02000000000000 1984-01-01 353.02000000000000 1985-01-01 353.02000000000000 1986-01-01 353.02000000000000 1987-01-01 353.02000000000000 1988-01-01 134.43700000000000 1989-01-01 171.84500000000000 1990-01-01 159.33900000000000 1991-01-01 112.80000000000000 1992-01-01 90.93220000000000 1993-01-01 104.61500000000000 1994-01-01 115.41900000000000 1995-01-01 117.97100000000000 1996-01-01 126.84899999999999 1997-01-01 130.95600000000002 1998-01-01 142.50799999999998 1999-01-01 161.87300000000000 2000-01-01 180.87700000000000 2001-01-01 192.55200000000002 2002-01-01 191.25799999999998 2003-01-01 204.58400000000000 2004-01-01 213.00000000000000 2005-01-01 224.59099999999998 2006-01-01 232.43099999999998 2007-01-01 240.31300000000000 2008-01-01 224.20100000000000 2009-01-01 210.07600000000000 2010-01-01 224.19600000000000 2011-01-01 236.12700000000000 2012-01-01 229.21500000000000 2013-01-01 232.21200000000002 2014-01-01 241.61200000000000 2015-01-01 242.33000000000000