Frequencies for first 10,000 rows of prov1910 variable in pos1994 dataset :

        140 |
   virology |      Freq.     Percent        Cum.
------------+-----------------------------------
            |      8,798       87.98       87.98
          N |      1,072       10.72       98.70
          Y |        130        1.30      100.00
------------+-----------------------------------
      Total |     10,000      100.00

by Jean Roth , jroth@nber.org , 17 May 2017