Frequencies for first 10,000 rows of prov1930 variable in pos1995 dataset :

  220   gen |
 immunology |      Freq.     Percent        Cum.
------------+-----------------------------------
            |      8,884       88.84       88.84
          N |        450        4.50       93.34
          Y |        666        6.66      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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