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

Hemoglobino |
      pathy |      Freq.     Percent        Cum.
------------+-----------------------------------
          1 |          3        0.03        0.03
          2 |      9,989       99.89       99.92
          8 |          1        0.01       99.93
          9 |          7        0.07      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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