Frequencies for first 10,000 rows of congenrflg variable in natl1970 dataset :

 Congenital |
Malformatio |
     ns (by |
State) flag |      Freq.     Percent        Cum.
------------+-----------------------------------
          0 |         69        0.69        0.69
          1 |      9,931       99.31      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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