Frequencies for first 10,000 rows of rh variable in linkco1991us_num dataset :

         Rh |
sensitizati |
         on |      Freq.     Percent        Cum.
------------+-----------------------------------
          1 |         40        0.40        0.40
          2 |      9,679       96.79       97.19
          8 |          1        0.01       97.20
          9 |        280        2.80      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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