Frequencies for first 10,000 rows of no_congen variable in natlterr2015 dataset :

         No |
 Congenital |
  Anomalies |
  Checked 1 |
       True |      Freq.     Percent        Cum.
------------+-----------------------------------
          0 |         20        0.20        0.20
          1 |      8,788       87.88       88.08
          9 |        114        1.14       89.22
          . |      1,078       10.78      100.00
------------+-----------------------------------
      Total |     10,000      100.00

by Jean Roth , jroth@nber.org , 20 Oct 2016