Frequencies for first 10,000 rows of omphalo variable in natl1998 dataset :

Omphalocele |
/Gastroschi |
        sis |      Freq.     Percent        Cum.
------------+-----------------------------------
          1 |          6        0.06        0.06
          2 |      9,978       99.78       99.84
          9 |         16        0.16      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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