Year Measure 1971 448.03223 1972 454.0609 1973 447.47951 1974 445.52532 1975 447.90666 1976 460.91352 1977 448.81573 1978 458.60736 1979 443.53999 1980 430.92115 1981 410.79647 1982 391.60225 1983 366.32805 1984 358.25527 1985 361.67141 1986 386.31788 1987 380.60098 1988 373.65895 1989 373.17538 1990 354.19018 1991 351.68971 1992 370.36344 1993 370.61086 1994 367.33449 1995 354.44865 1996 386.06855 1997 382.43502 1998 370.93334 1999 430.97777 2000 406.91039 2001 383.21659 2002 401.9088 2003 373.22436 2004 516.67693 2005 524.55661 2006 505.82036 2007 533.39927 2008 524.7881 2009 470.34199 2010 498.14573 2011 557.60185 2012 589.79416 2013 615.92852 2014 615.80331