Airborne Fraction (%)
 year  Annual 7yr_mean
 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   56.02
 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   53.22   57.49
 1976   24.48   58.45
 1977   76.73   57.22
 1978   70.83   59.19
 1979   56.77   56.06
 1980   82.64   62.56
 1981   49.66   60.49
 1982   31.30   58.62
 1983   69.96   58.29
 1984   62.28   55.56
 1985   57.71   61.15
 1986   54.47   64.85
 1987   63.52   61.23
 1988   88.84   58.93
 1989   57.14   54.21
 1990   44.62   50.12
 1991   46.21   48.47
 1992   24.65   44.69
 1993   25.83   44.84
 1994   51.98   43.65
 1995   62.40   49.50
 1996   58.19   55.54
 1997   36.31   57.07
 1998   87.12   56.82
 1999   66.94   56.55
 2000   36.55   58.72
 2001   50.23   60.69
 2002   60.51   55.96
 2003   73.37   54.38
 2004   50.10   55.44
 2005   54.01   55.70
 2006   55.91   52.32
 2007   43.97   49.47
 2008   52.05   48.43
 2009   36.86   47.18
 2010   53.38   47.92
 2011   42.80   47.76
 2012   45.29   47.61
 2013   61.11   53.03
 2014   42.85   52.03
 2015   50.96   53.10
 2016   74.81   54.01
 2017   46.41   52.66
 2018   50.27   53.28
 2019   51.62   52.97
 2020   51.67 *******
 2021   47.23 *******
 2022   48.80 *******