Frequencies for first 10,000 rows of gestestm variable in natlterr1997 dataset :

   Clinical |
Estimate of |
  Gestation |
       Flag |      Freq.     Percent        Cum.
------------+-----------------------------------
          1 |        144        1.44        1.44
          . |      9,856       98.56      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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