Frequencies for first 10,000 rows of uab_hyal variable in natl2005 dataset :

    Hyaline |
   Membrane |
  Disease U |      Freq.     Percent        Cum.
------------+-----------------------------------
          1 |         18        0.18        0.18
          2 |      9,853       98.53       98.71
          9 |        129        1.29      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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