Frequencies for first 10,000 rows of f_cigs_0 variable in natl2009 dataset :

 Cigarettes |
     before |
  Pregnancy |
  (cig_0) R |      Freq.     Percent        Cum.
------------+-----------------------------------
          0 |      9,962       99.62       99.62
          1 |         38        0.38      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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