exposure        nma
     "high"         28
     "high"         35
     "high"         37
     "high"         37
     "high"       43.5
     "high"         44
     "high"       45.5
     "high"         46
     "high"         48
     "high"       48.3
     "high"       48.7
     "high"         51
     "high"         52
     "high"         53
     "high"         53
     "high"         54
     "high"         54
     "high"         55
      "low"       34.5
      "low"       37.5
      "low"       39.5
      "low"         40
      "low"       45.5
      "low"         47
      "low"         47
      "low"       47.5
      "low"       48.7
      "low"         49
      "low"         51
      "low"         51
      "low"         52
      "low"         53
      "low"         54
      "low"         54
      "low"         55
      "low"       56.5
      "low"         57
      "low"       58.5
      "low"       58.5