Year Measure 1960 1827.93682 1961 1894.05744 1962 1976.85979 1963 1984.01674 1964 2031.26137 1965 2088.01079 1966 2140.86869 1967 2199.05462 1968 2290.23626 1969 2438.36689 1970 2549.98038 1971 2627.02149 1972 2693.74528 1973 2784.33271 1974 2882.11696 1975 3029.42782 1976 3157.94611 1977 3251.80257 1978 3488.40641 1979 3565.32514 1980 3559.32651 1981 3245.29782 1982 3412.49866 1983 3350.91951 1984 3211.69685 1985 3351.95416 1986 3464.24289 1987 3535.48197 1988 3496.98511 1989 3259.2233 1990 2705.60874 1991 2641.02945 1992 2569.17533 1993 2624.64884 1994 2496.17271 1995 2577.52968 1996 2680.10207 1997 2643.12354 1998 2459.83454 1999 2396.69212 2000 2320.37672 2001 2336.44584 2002 2314.20258 2003 2375.00613 2004 2383.05568 2005 2414.16179 2006 2536.97805 2007 2527.40841 2008 2564.77564 2009 2466.52404 2010 2640.23891 2011 2653.40366 2012 2566.57431 2013 2565.67046 2014 2473.40688 2015 2490.20642