Frequencies for first 10,000 rows of obgest_flg variable in natlterr2013 dataset :

   Clinical |
Estimate of |
  Gestation |
  Used Flag |
        U;R |      Freq.     Percent        Cum.
------------+-----------------------------------
          1 |      1,890       18.90       18.90
          . |      8,110       81.10      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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