Frequencies for first 10,000 rows of gestwk variable in namcs2006 dataset :

       week of |
     gestation |      Freq.     Percent        Cum.
---------------+-----------------------------------
             1 |          1        0.01        0.01
             2 |          2        0.02        0.03
             3 |          1        0.01        0.04
             4 |          1        0.01        0.05
             5 |          3        0.03        0.08
             6 |          1        0.01        0.09
             7 |          3        0.03        0.12
             8 |          2        0.02        0.14
             9 |          5        0.05        0.19
            10 |          3        0.03        0.22
            12 |          1        0.01        0.23
            13 |          1        0.01        0.24
            14 |          2        0.02        0.26
            15 |          4        0.04        0.30
            16 |          3        0.03        0.33
            17 |          2        0.02        0.35
            18 |          1        0.01        0.36
            19 |          3        0.03        0.39
            20 |          3        0.03        0.42
            21 |          4        0.04        0.46
            23 |          1        0.01        0.47
            24 |          3        0.03        0.50
            25 |          5        0.05        0.55
            26 |          3        0.03        0.58
            27 |          3        0.03        0.61
            28 |          9        0.09        0.70
            29 |          5        0.05        0.75
            30 |          3        0.03        0.78
            31 |          3        0.03        0.81
            32 |          2        0.02        0.83
            33 |          7        0.07        0.90
            34 |          3        0.03        0.93
            35 |          7        0.07        1.00
            36 |          7        0.07        1.07
            37 |          4        0.04        1.11
            38 |          1        0.01        1.12
            39 |          7        0.07        1.19
            40 |          3        0.03        1.22
not applicable |      8,947       89.47       90.69
         blank |        931        9.31      100.00
---------------+-----------------------------------
         Total |     10,000      100.00

by Jean Roth , jroth@nber.org , 28 Mar 2016