Frequencies for first 10,000 rows of uab_hyal variable in linkpe2009psden dataset :

    Hyaline |
   Membrane |
  Disease U |      Freq.     Percent        Cum.
------------+-----------------------------------
          . |     10,000      100.00      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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