Year Measure 1960 320.17283 1961 350.1948 1962 379.14228 1963 409.83992 1964 459.52764 1965 486.85378 1966 543.0529 1967 572.42533 1968 614.59942 1969 681.11452 1970 763.90216 1971 835.28503 1972 911.54207 1973 994.77592 1974 1080.94648 1975 1075.82694 1976 1136.94057 1977 1248.9854 1978 1343.656 1979 1466.47463 1980 1558.52076 1981 1567.29597 1982 1644.71112 1983 1740.03162 1984 1774.26854 1985 1873.17687 1986 1974.53655 1987 2057.72046 1988 2201.7823 1989 2399.30035 1990 2541.86576 1991 2676.64367 1992 2815.87711 1993 2803.20231 1994 2870.83303 1995 3076.84605 1996 3195.86405 1997 3352.46583 1998 3545.01035 1999 3795.22928 2000 3988.96082 2001 4119.67049 2002 4271.16853 2003 4375.73222 2004 4533.53969 2005 4682.99101 2006 4827.46718 2007 4890.56019 2008 4850.83741 2009 4843.84969 2010 4959.09431 2011 4848.27934 2012 4736.35177 2013 4685.05479 2014 4662.6008