Frequencies for first 10,000 rows of cig_2 variable in natlterr2007 dataset :

 Cigarettes |
        2nd |
  Trimester |
        RFP |
575=f_tobac |
        o R |      Freq.     Percent        Cum.
------------+-----------------------------------
          0 |      3,833       38.33       38.33
          4 |          1        0.01       38.34
         10 |          2        0.02       38.36
         99 |          1        0.01       38.37
          . |      6,163       61.63      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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