Year Measure 1960 1318.81249 1961 1396.46615 1962 1412.72968 1963 1453.96211 1964 1522.19497 1965 1511.90491 1966 1629.59187 1967 1767.42511 1968 1881.14935 1969 1974.58885 1970 2023.63108 1971 2245.32344 1972 2194.51306 1973 2238.47178 1974 2268.08988 1975 2083.99492 1976 2110.19194 1977 2203.82152 1978 2178.72098 1979 2534.33864 1980 2413.15635 1981 2392.95395 1982 2356.89426 1983 2336.18356 1984 2346.17853 1985 2438.4384 1986 2503.49889 1987 2608.80658 1988 2592.83865 1989 2655.24497 1990 2820.41017 1991 2827.8445 1992 2775.218 1993 2813.71046 1994 2941.61324 1995 2951.91309 1996 3122.33561 1997 3255.49845 1998 3417.56853 1999 3544.38762 2000 3626.74716 2001 3713.51387 2002 3661.32224 2003 3515.0945 2004 3558.08594 2005 3503.64286 2006 3424.16085 2007 3416.03095 2008 3293.88464 2009 3149.56514 2010 3152.00361 2011 2865.37474 2012 2853.06487 2013 2814.98269 2014 2741.57488 2015 2819.87585