Year Measure 1960 1398.65484 1961 1454.75512 1962 1568.91106 1963 1869.5875 1964 1819.43534 1965 1943.60052 1966 1966.69214 1967 2040.8279 1968 2172.60388 1969 2334.44403 1970 2556.65871 1971 2637.67078 1972 2727.71922 1973 2998.00518 1974 2783.51454 1975 2710.77292 1976 2821.01289 1977 2877.79291 1978 2995.01682 1979 3042.17916 1980 3170.57547 1981 3093.32328 1982 2984.22326 1983 3173.30758 1984 3239.36997 1985 3412.39111 1986 3544.52206 1987 3430.85551 1988 3436.87583 1989 3339.08347 1990 3627.69281 1991 3637.19412 1992 3613.28433 1993 3490.88655 1994 3494.44715 1995 3421.65104 1996 3473.2063 1997 3525.8913 1998 3557.99008 1999 3547.37289 2000 3480.59157 2001 3673.29257 2002 3553.74026 2003 3542.0656 2004 3530.57834 2005 3488.21835 2006 3619.15164 2007 3410.81988 2008 3499.79098 2009 3481.85285 2010 3347.61836 2011 3205.32827 2012 3202.83434 2013 3304.11544 2014 3059.93675 2015 2960.07339