Frequencies for first 10,000 rows of no_congen variable in natl2014 dataset :

         No |
 Congenital |
  Anomalies |
  Checked 1 |
       True |      Freq.     Percent        Cum.
------------+-----------------------------------
          0 |         52        0.52        0.52
          1 |      9,948       99.48      100.00
------------+-----------------------------------
      Total |     10,000      100.00

by Jean Roth , jroth@nber.org , 15 Jun 2016