Year Measure 1971 539.75709 1972 540.58879 1973 571.37598 1974 553.28227 1975 528.1154 1976 547.69689 1977 580.53094 1978 631.20376 1979 623.46137 1980 655.4233 1981 636.17331 1982 630.6502 1983 626.71804 1984 620.0672 1985 615.16777 1986 622.94088 1987 699.10224 1988 726.93124 1989 770.89001 1990 729.2193 1991 733.72477 1992 712.69166 1993 722.22716 1994 770.8221 1995 824.55822 1996 824.76234 1997 877.04524 1998 847.18302 1999 791.64573 2000 726.27039 2001 724.96275 2002 705.43427 2003 707.14646 2004 701.88999 2005 683.2006 2006 693.56799 2007 708.78299 2008 732.88412 2009 732.69034 2010 774.22065 2011 774.70323 2012 783.32834 2013 764.12909 2014 788.68962