Year Measure 1960 1546.26147 1961 1554.03491 1962 1675.87362 1963 1823.99523 1964 1855.08516 1965 1851.84356 1966 1902.75641 1967 1920.21212 1968 2045.82812 1969 2181.63231 1970 2418.21013 1971 2508.52092 1972 2627.3225 1973 2830.9468 1974 2730.43733 1975 2654.84873 1976 2866.97592 1977 2797.42192 1978 2893.0223 1979 3138.91614 1980 3067.01192 1981 2897.0094 1982 2830.22178 1983 2843.40557 1984 2953.68815 1985 3051.59706 1986 3061.58886 1987 3174.74539 1988 3204.56218 1989 3138.98349 1990 3240.11136 1991 3415.17308 1992 3245.59208 1993 3255.7847 1994 3234.49299 1995 3373.60357 1996 3580.4208 1997 3550.40417 1998 3606.61038 1999 3591.80947 2000 3570.49883 2001 3758.45757 2002 3773.65173 2003 3973.62433 2004 4007.5699 2005 4085.56765 2006 4078.81223 2007 4019.59017 2008 4032.14843 2009 3798.15117 2010 4051.19602 2011 3921.90051 2012 3886.76773 2013 3919.04442 2014 3763.3279 2015 3800.29942