Frequencies for first 10,000 rows of tracheo variable in natl1989 dataset :

  Tracheo - |
 esophageal |
fistula/Eso |
    phageal |
    atresia |      Freq.     Percent        Cum.
------------+-----------------------------------
          1 |          2        0.02        0.02
          2 |      9,761       97.61       97.63
          9 |        237        2.37      100.00
------------+-----------------------------------
      Total |     10,000      100.00

by Jean Roth , jroth@nber.org , 3 Jan 2016