Year Measure 1960 7681.14052 1961 8404.62075 1962 9390.97831 1963 9658.7052 1964 10553.44407 1965 11416.35296 1966 11655.97126 1967 12256.97502 1968 13494.8746 1969 13230.21737 1970 13454.12503 1971 14084.40961 1972 14488.41649 1973 15541.79001 1974 16286.77491 1975 16313.92407 1976 16913.42006 1977 16515.36343 1978 17314.78112 1979 18862.29081 1980 18725.67689 1981 19431.16841 1982 19357.74561 1983 20497.37043 1984 21939.81352 1985 22559.09429 1986 22177.62158 1987 22800.13518 1988 22979.99187 1989 22859.30047 1990 23353.91502 1991 23808.62992 1992 23787.32181 1993 23967.11867 1994 24247.26394 1995 24528.44386 1996 23998.84419 1997 24326.03424 1998 25424.10364 1999 25057.1896 2000 24993.7263 2001 25590.68943 2002 24620.33613 2003 23201.39413 2004 24214.10698 2005 25083.21453 2006 24099.93226 2007 24855.00046 2008 24866.13431 2009 23859.70958 2010 24890.92401 2011 23510.38383 2012 24070.98592 2013 23806.88488 2014 22999.9346