Dummy OMI values for 2013-2019 and 2020 and 2020AF in Beijing
      Min     Max       Mean     
BF  35.624   49.617    41.336       
DF  22.685   32.358    25.729
AF  24.325   33.284    29.347

BF  14.380   50.285    30.671      
DF  8.085    22.784    13.445
AF  8.074    21.694    14.363
AF1 23.862   38.278    29.723
AF2 2.388    19.189    13.856
AF3 3.902    9.801     7.466
AF4 8.013    9.639     8.996
AF5 7.907    8.526     8.256
AF6 7.613    12.896    9.439
