Frequencies for first 10,000 rows of injprev variable in nhamcsopd2005 dataset :

     injury |
 prevention |      Freq.     Percent        Cum.
------------+-----------------------------------
         no |      9,729       97.29       97.29
        yes |        271        2.71      100.00
------------+-----------------------------------
      Total |     10,000      100.00

by Jean Roth , jroth@nber.org , 28 Mar 2016