Frequencies for first 10,000 rows of hivser variable in nhamcsed2005 dataset :

        hiv |
   serology |      Freq.     Percent        Cum.
------------+-----------------------------------
         no |      9,871       98.71       98.71
        yes |        129        1.29      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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