Frequencies for first 10,000 rows of prov1930 variable in pos1991 dataset :

* 220   gen |
 immunology |      Freq.     Percent        Cum.
------------+-----------------------------------
            |      8,536       85.36       85.36
          N |        545        5.45       90.81
          Y |        919        9.19      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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