Frequencies for first 10,000 rows of inj_sev variable in person dataset :

     INJURY |
   SEVERITY |      Freq.     Percent        Cum.
------------+-----------------------------------
          0 |      2,143       21.43       21.43
          1 |        649        6.49       27.92
          2 |      1,355       13.55       41.47
          3 |      1,715       17.15       58.62
          4 |      4,037       40.37       98.99
          5 |         16        0.16       99.15
          6 |          2        0.02       99.17
          9 |         83        0.83      100.00
------------+-----------------------------------
      Total |     10,000      100.00

by Jean Roth , jroth@nber.org , 18 Apr 2016