Frequencies for first 10,000 rows of lmpused variable in natlterr2014 dataset :

   Combined |
  Gestation |
  Used Flag |
      Blank |
   Combined |
  gestation |
   not used |      Freq.     Percent        Cum.
------------+-----------------------------------
          1 |         34        0.34        0.34
          . |      9,966       99.66      100.00
------------+-----------------------------------
      Total |     10,000      100.00

by Jean Roth , jroth@nber.org , 15 Jun 2016