Frequencies for first 10,000 rows of lmpused variable in natl2017 dataset :

   Combined |
  Gestation |
  Used Flag |
      Blank |
   Combined |
  gestation |
   not used |      Freq.     Percent        Cum.
------------+-----------------------------------
          1 |         12        0.12        0.12
          . |      9,988       99.88      100.00
------------+-----------------------------------
      Total |     10,000      100.00

by Jean Roth , jroth@nber.org , 19 Sep 2018