Frequencies for first 10,000 rows of prov1980 variable in pos1991 dataset :

   520   rh |
     titers |      Freq.     Percent        Cum.
------------+-----------------------------------
            |      8,536       85.36       85.36
          N |      1,196       11.96       97.32
          Y |        268        2.68      100.00
------------+-----------------------------------
      Total |     10,000      100.00

by Jean Roth , jroth@nber.org , 26 Jan 2016