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

     Injury |
   Severity |      Freq.     Percent        Cum.
------------+-----------------------------------
          0 |      2,097       20.97       20.97
          1 |        564        5.64       26.61
          2 |      1,304       13.04       39.65
          3 |      1,810       18.10       57.75
          4 |      4,203       42.03       99.78
          9 |         22        0.22      100.00
------------+-----------------------------------
      Total |     10,000      100.00

by Jean Roth , jroth@nber.org , 22 Apr 2016