Frequencies for first 10,000 rows of rh variable in natl1991 dataset :

         Rh |
sensitizati |
         on |      Freq.     Percent        Cum.
------------+-----------------------------------
          1 |         31        0.31        0.31
          2 |      9,962       99.62       99.93
          9 |          7        0.07      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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