Year Measure 1960 2196.95307 1961 2252.77869 1962 2361.74388 1963 2478.91201 1964 2678.38317 1965 2887.69411 1966 3065.43868 1967 3126.42605 1968 3342.70326 1969 3668.5233 1970 3872.22302 1971 3939.21109 1972 4188.16068 1973 4507.55698 1974 4383.84812 1975 4181.81066 1976 4459.85961 1977 4516.24807 1978 4664.52318 1979 4963.53551 1980 5146.6423 1981 4934.58847 1982 4805.49388 1983 4823.85883 1984 4910.52302 1985 5269.89237 1986 5482.57842 1987 5960.69259 1988 5590.43651 1989 5753.63928 1990 5691.57119 1991 5742.78423 1992 5380.99307 1993 5617.21538 1994 5972.55427 1995 5661.90388 1996 6070.21209 1997 6276.95169 1998 6319.3266 1999 6283.95826 2000 6262.19208 2001 6410.62523 2002 6728.58141 2003 7077.02665 2004 7134.85421 2005 6562.02231 2006 7111.85682 2007 6974.89676 2008 6669.17335 2009 6268.30055 2010 6828.78375 2011 6537.6373 2012 6275.77096 2013 6116.22729 2014 6213.35777 2015 5924.70012