Frequencies for first 10,000 rows of f_cigs_0 variable in natl2011 dataset :

 Cigarettes |
     before |
  Pregnancy |
  (cig_0) R |      Freq.     Percent        Cum.
------------+-----------------------------------
          0 |      9,985       99.85       99.85
          1 |         15        0.15      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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