Frequencies for first 10,000 rows of rh variable in natlterr1997 dataset :

         Rh |
sensitizati |
         on |      Freq.     Percent        Cum.
------------+-----------------------------------
          1 |         23        0.23        0.23
          2 |      9,973       99.73       99.96
          9 |          4        0.04      100.00
------------+-----------------------------------
      Total |     10,000      100.00

by Jean Roth , jroth@nber.org , 22 Dec 2015