Frequencies for first 10,000 rows of cig_2 variable in natlterr2006 dataset :

 Cigarettes |
        2nd |
  Trimester |
        RFP |
575=f_tobac |
        o R |      Freq.     Percent        Cum.
------------+-----------------------------------
          0 |      3,723       37.23       37.23
          1 |          1        0.01       37.24
         60 |          1        0.01       37.25
          . |      6,275       62.75      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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