Frequencies for first 10,000 rows of prov1930 variable in pos1994 dataset :

  220   gen |
 immunology |      Freq.     Percent        Cum.
------------+-----------------------------------
            |      8,798       87.98       87.98
          N |        479        4.79       92.77
          Y |        723        7.23      100.00
------------+-----------------------------------
      Total |     10,000      100.00

by Jean Roth , jroth@nber.org , 17 May 2017