Frequencies for first 10,000 rows of anen variable in natl2002 dataset :

Anencephalu |
          s |      Freq.     Percent        Cum.
------------+-----------------------------------
          1 |          1        0.01        0.01
          2 |      9,584       95.84       95.85
          9 |        415        4.15      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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