Frequencies for first 10,000 rows of gestestm variable in natl1997 dataset :

   Clinical |
Estimate of |
  Gestation |
       Flag |      Freq.     Percent        Cum.
------------+-----------------------------------
          1 |        433        4.33        4.33
          . |      9,567       95.67      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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