Year Measure 1971 1870.10916 1972 1756.331 1973 2368.43685 1974 1732.93337 1975 2032.7644 1976 1832.14803 1977 1786.48768 1978 1849.39919 1979 2005.81352 1980 2017.27695 1981 1840.73534 1982 1958.31704 1983 1793.92205 1984 1828.53907 1985 1788.99669 1986 2102.24587 1987 2278.47929 1988 2451.74584 1989 2488.92342 1990 2460.46545 1991 2324.5393 1992 2580.96935 1993 2634.67402 1994 2738.3997 1995 2796.25158 1996 2801.20836 1997 2881.12834 1998 2885.72651 1999 2737.73665 2000 2899.42662 2001 2973.04271 2002 2862.79574 2003 2949.30042 2004 2821.99692 2005 2661.44919 2006 2882.39902 2007 2898.15337 2008 3129.12776 2009 2873.87611 2010 3042.43402 2011 2980.17616 2012 3067.74249 2013 2870.09877 2014 2762.50593 2015 2777.87532