Frequencies for first 10,000 rows of obgest_flg variable in linkpe2009psden dataset :

   Clinical |
Estimate of |
  Gestation |
  Used Flag |
        U;R |      Freq.     Percent        Cum.
------------+-----------------------------------
          1 |        285        2.85        2.85
          . |      9,715       97.15      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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