Frequencies for first 10,000 rows of omphalo variable in linkco1991us_num dataset :

Omphalocele |
/Gastroschi |
        sis |      Freq.     Percent        Cum.
------------+-----------------------------------
          1 |         37        0.37        0.37
          2 |      9,690       96.90       97.27
          9 |        273        2.73      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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