Year Measure 1971 30.18691 1972 31.9854 1973 33.56661 1974 33.79144 1975 34.22964 1976 34.86263 1977 34.9049 1978 34.2343 1979 36.66506 1980 36.61052 1981 37.5575 1982 35.54273 1983 33.71553 1984 34.33521 1985 36.03975 1986 40.37982 1987 40.77844 1988 44.37482 1989 46.67369 1990 51.17911 1991 54.2656 1992 52.93976 1993 48.27824 1994 49.19057 1995 57.07462 1996 60.56111 1997 55.03354 1998 59.84276 1999 55.38945 2000 57.93193 2001 61.59407 2002 66.83135 2003 66.65039 2004 77.98696 2005 77.66957 2006 63.61519 2007 79.35843 2008 83.52179 2009 69.85456 2010 92.95295 2011 83.85378 2012 93.75956 2013 95.97802 2014 99.16747