Year Measure 1971 1632.08419 1972 1786.72073 1973 1906.92111 1974 2018.98016 1975 2214.61085 1976 2418.74932 1977 2550.13583 1978 2664.74254 1979 2694.10074 1980 2872.09444 1981 2946.26376 1982 2922.09031 1983 2971.16402 1984 3077.86832 1985 3129.89073 1986 3315.72283 1987 3275.68049 1988 3392.62498 1989 3412.00455 1990 2924.59627 1991 2521.00384 1992 2319.57275 1993 2272.12423 1994 2234.73508 1995 2328.79436 1996 2430.30153 1997 2250.9998 1998 2107.44546 1999 1935.56081 2000 1987.66019 2001 2066.78393 2002 2079.79606 2003 2237.93782 2004 2295.57051 2005 2365.41956 2006 2446.28608 2007 2529.90689 2008 2605.81974 2009 2390.57474 2010 2550.86329 2011 2639.03343 2012 2604.24314 2013 2494.53392 2014 2584.41179