Frequencies for first 10,000 rows of anen variable in natl1989 dataset :

Anencephalu |
          s |      Freq.     Percent        Cum.
------------+-----------------------------------
          1 |          1        0.01        0.01
          2 |      9,762       97.62       97.63
          9 |        237        2.37      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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