Year Percent 1960-01-01 55.47350000000000 1961-01-01 51.28550000000000 1962-01-01 61.53960000000000 1963-01-01 73.73560000000000 1964-01-01 73.78320000000000 1965-01-01 76.70030000000000 1966-01-01 76.42000000000000 1967-01-01 75.15330000000000 1968-01-01 73.28750000000000 1969-01-01 72.11480000000000 1970-01-01 82.37700000000001 1971-01-01 102.76500000000000 1972-01-01 109.75100000000000 1973-01-01 109.65899999999999 1974-01-01 110.97700000000000 1975-01-01 111.67200000000001 1976-01-01 112.60200000000000 1977-01-01 112.69100000000000 1978-01-01 111.87200000000001 1979-01-01 111.98100000000001 1980-01-01 115.35000000000000 1981-01-01 116.73700000000001 1982-01-01 121.03600000000000 1983-01-01 126.47900000000000 1984-01-01 129.04300000000000 1985-01-01 130.66899999999998 1986-01-01 136.32700000000000 1987-01-01 146.90800000000000 1988-01-01 154.68300000000000 1989-01-01 161.08700000000002 1990-01-01 164.83200000000000 1991-01-01 166.71500000000000 1992-01-01 170.47099999999998 1993-01-01 174.56500000000000 1994-01-01 174.96099999999998 1995-01-01 173.80000000000000 1996-01-01 172.44700000000000 1997-01-01 178.92500000000000 1998-01-01 189.03000000000000 1999-01-01 192.46700000000000 2000-01-01 186.50799999999998 2001-01-01 185.00599999999997 2002-01-01 183.65599999999998 2003-01-01 181.04900000000000 2004-01-01 175.99099999999999 2005-01-01 171.97799999999998 2006-01-01 170.32100000000000 2007-01-01 163.80000000000000 2008-01-01 163.59500000000000 2009-01-01 168.50300000000000 2010-01-01 161.51400000000000 2011-01-01 160.89000000000000 2012-01-01 158.75200000000000 2013-01-01 158.53900000000000 2014-01-01 160.68500000000000 2015-01-01 159.28200000000000 2016-01-01 159.99800000000000