Frequencies for first 10,000 rows of uca_trach variable in natl2003 dataset :

Tracheo-Eso |
    phageal |
  Fistula U |      Freq.     Percent        Cum.
------------+-----------------------------------
          1 |          2        0.02        0.02
          2 |      9,042       90.42       90.44
          8 |          8        0.08       90.52
          9 |        948        9.48      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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