Frequencies for first 10,000 rows of prov1975 variable in pos1995 dataset :

510   abo + |
   rh group |      Freq.     Percent        Cum.
------------+-----------------------------------
            |      8,884       88.84       88.84
          N |        827        8.27       97.11
          Y |        289        2.89      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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