Year Measure 1960 1922.97367 1961 2023.30839 1962 2296.28956 1963 2502.92764 1964 2600.15582 1965 2822.73484 1966 3067.42783 1967 3061.11011 1968 3203.75228 1969 3699.53044 1970 3971.43073 1971 3728.53802 1972 3858.59212 1973 3781.7572 1974 3489.60646 1975 3453.20722 1976 3745.56184 1977 3830.10381 1978 3894.63776 1979 4020.03654 1980 3735.14409 1981 3381.43445 1982 3422.3748 1983 3233.1601 1984 3353.4612 1985 3774.10113 1986 3823.50181 1987 3819.83213 1988 3642.11965 1989 3414.21161 1990 3376.78331 1991 3734.8184 1992 3561.89037 1993 3645.51535 1994 3760.57724 1995 3706.44019 1996 4170.25202 1997 3848.15584 1998 3772.11028 1999 3602.67064 2000 3489.6148 2001 3583.95572 2002 3535.09801 2003 3727.83418 2004 3597.17296 2005 3487.63191 2006 3728.17104 2007 3622.59683 2008 3501.51385 2009 3329.21107 2010 3510.79685 2011 3230.18803 2012 3091.58158 2013 3125.33776 2014 2872.57355 2015 2816.61457