Frequencies for first 10,000 rows of rh variable in natl1997 dataset :

         Rh |
sensitizati |
         on |      Freq.     Percent        Cum.
------------+-----------------------------------
          1 |         74        0.74        0.74
          2 |      9,917       99.17       99.91
          9 |          9        0.09      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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