Frequencies for first 10,000 rows of prov1930 variable in pos1993 dataset :

  220   gen |
 immunology |      Freq.     Percent        Cum.
------------+-----------------------------------
            |      8,797       87.97       87.97
          N |        480        4.80       92.77
          Y |        723        7.23      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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