Frequencies for first 10,000 rows of hivser variable in nhamcsopd1996 dataset :

        hiv |
   serology |      Freq.     Percent        Cum.
------------+-----------------------------------
          0 |      9,863       98.63       98.63
          1 |        137        1.37      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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