Frequencies for first 10,000 rows of uab_hyal variable in natlterr2003 dataset :

    Hyaline |
   Membrane |
  Disease U |      Freq.     Percent        Cum.
------------+-----------------------------------
          1 |         34        0.34        0.34
          2 |      9,942       99.42       99.76
          8 |         23        0.23       99.99
          9 |          1        0.01      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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