Frequencies for first 10,000 rows of cig_2 variable in natlterr2011 dataset :

 Cigarettes |
        2nd |
  Trimester |
        RFP |
575=f_tobac |
        o R |      Freq.     Percent        Cum.
------------+-----------------------------------
          0 |      5,688       56.88       56.88
          1 |          3        0.03       56.91
          2 |          7        0.07       56.98
          3 |          7        0.07       57.05
          4 |          5        0.05       57.10
          5 |         13        0.13       57.23
          6 |          7        0.07       57.30
          7 |          5        0.05       57.35
          9 |          2        0.02       57.37
         10 |         27        0.27       57.64
         12 |          1        0.01       57.65
         15 |          1        0.01       57.66
         16 |          1        0.01       57.67
         20 |          9        0.09       57.76
         99 |      1,688       16.88       74.64
          . |      2,536       25.36      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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