Frequencies for first 10,000 rows of gestestm variable in natlterr2002 dataset :

   Clinical |
Estimate of |
  Gestation |
  Used Flag |      Freq.     Percent        Cum.
------------+-----------------------------------
          1 |        181        1.81        1.81
          . |      9,819       98.19      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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