Year Measure 1971 40.32738 1972 37.67331 1973 39.33078 1974 33.8846 1975 38.86771 1976 46.29772 1977 53.22252 1978 53.98414 1979 52.81206 1980 53.88752 1981 54.21755 1982 56.59401 1983 55.93936 1984 64.80804 1985 67.83034 1986 70.81382 1987 77.47181 1988 84.43863 1989 91.36066 1990 94.94264 1991 98.44856 1992 101.48959 1993 111.65866 1994 128.83313 1995 152.51537 1996 179.12155 1997 202.05715 1998 231.96084 1999 252.16845 2000 285.28168 2001 324.93254 2002 375.61391 2003 430.86414 2004 481.26562 2005 566.7377 2006 641.5917 2007 724.10405 2008 798.25574 2009 901.25773 2010 1016.59824 2011 1095.83718 2012 1197.64231 2013 1266.45772 2014 1410.91491