Year Measure 1960 10523.40669 1961 10534.01821 1962 10414.54092 1963 10465.81302 1964 11150.05034 1965 10926.39517 1966 10480.60618 1967 10361.97257 1968 11114.66726 1969 11974.19259 1970 12106.15294 1971 11863.08959 1972 12009.57011 1973 12648.56042 1974 13023.88959 1975 10504.9812 1976 10668.56744 1977 10278.55755 1978 11096.00367 1979 10458.11286 1980 9774.65056 1981 8526.03737 1982 8057.81 1983 7576.20712 1984 8112.67548 1985 8346.92642 1986 8163.54875 1987 7942.94808 1988 8158.43353 1989 8699.93636 1990 8874.10502 1991 9353.42119 1992 9262.08198 1993 9266.94258 1994 8823.25247 1995 7705.40716 1996 7711.17871 1997 7409.851 1998 7066.88486 1999 7266.97253 2000 7676.83704 2001 7982.85035 2002 8204.72684 2003 8549.50291 2004 9387.4371 2005 9428.81129 2006 9170.53257 2007 8773.8967 2008 8612.23371 2009 7951.72394 2010 8329.47828 2011 8056.4043 2012 7722.1902 2013 7312.154 2014 6861.10667 2015 6548.40556