Airborne Fraction (%) --------------------- year annual 7yrmn --------------------- 1960 73.67 57.98 1961 54.40 56.40 1962 55.42 54.99 1963 48.79 57.16 1964 40.47 53.08 1965 39.41 51.53 1966 87.96 53.18 1967 45.13 56.03 1968 43.53 56.60 1969 66.95 58.12 1970 68.73 58.59 1971 44.47 57.27 1972 50.05 58.65 1973 91.25 52.58 1974 35.88 53.73 1975 53.21 57.49 1976 24.48 59.87 1977 76.73 56.57 1978 70.83 58.49 1979 66.69 55.47 1980 68.20 61.97 1981 49.25 59.97 1982 32.15 58.15 1983 69.97 56.35 1984 62.69 55.79 1985 58.10 61.70 1986 54.09 65.32 1987 64.26 61.20 1988 90.64 58.75 1989 57.49 53.98 1990 41.16 49.83 1991 45.49 47.94 1992 24.71 43.76 1993 25.08 43.78 1994 51.04 43.07 1995 61.34 48.68 1996 57.66 54.88 1997 36.15 56.62 1998 84.79 56.35 1999 68.08 56.37 2000 37.30 58.65 2001 49.10 60.64 2002 61.54 56.21 2003 73.61 54.24 2004 50.04 55.13 2005 53.79 55.42 2006 54.27 51.97 2007 43.59 49.07 2008 51.11 47.90 2009 37.41 46.59 2010 53.30 47.44 2011 41.82 47.11 2012 44.64 46.78 2013 60.25 * 2014 41.28 * 2015 48.76 * ---------------------