Year Measure 1960 494.7956 1961 550.43633 1962 613.24745 1963 663.93685 1964 745.38437 1965 822.95674 1966 925.93069 1967 1033.07697 1968 1154.52678 1969 1293.58961 1970 1415.84102 1971 1534.9827 1972 1703.5083 1973 1873.67742 1974 2024.09527 1975 2054.34324 1976 2256.14102 1977 2294.47389 1978 2399.0301 1979 2528.94962 1980 2644.22298 1981 2671.28329 1982 2658.24167 1983 2792.15986 1984 2903.33794 1985 2975.08323 1986 3004.27963 1987 3094.08226 1988 3217.94816 1989 3442.94871 1990 3536.74997 1991 3607.70014 1992 3690.591 1993 3638.52663 1994 3756.0392 1995 3917.32464 1996 4008.93942 1997 4324.42065 1998 4479.04732 1999 4820.67503 2000 5167.80967 2001 5422.51569 2002 5576.54626 2003 5676.14049 2004 5892.30741 2005 6111.21922 2006 6105.07585 2007 6054.37444 2008 6025.77276 2009 5652.59593 2010 5706.56306 2011 5599.37737 2012 5573.40118 2013 5409.41134 2014 5355.98701