Frequencies for first 10,000 rows of gestwk variable in namcs2014 dataset :

Gestation week |      Freq.     Percent        Cum.
---------------+-----------------------------------
         Blank |      5,618       56.18       56.18
       Unknown |          1        0.01       56.19
Not applicable |      4,188       41.88       98.07
             2 |          4        0.04       98.11
             4 |          1        0.01       98.12
             6 |          4        0.04       98.16
             7 |          2        0.02       98.18
             8 |          4        0.04       98.22
             9 |          4        0.04       98.26
            10 |          6        0.06       98.32
            11 |          7        0.07       98.39
            12 |          2        0.02       98.41
            13 |          5        0.05       98.46
            14 |          2        0.02       98.48
            15 |          6        0.06       98.54
            16 |          2        0.02       98.56
            17 |          3        0.03       98.59
            18 |          1        0.01       98.60
            19 |          5        0.05       98.65
            20 |         10        0.10       98.75
            21 |          8        0.08       98.83
            22 |          5        0.05       98.88
            23 |          6        0.06       98.94
            24 |          3        0.03       98.97
            25 |          4        0.04       99.01
            26 |          4        0.04       99.05
            27 |          5        0.05       99.10
            28 |          4        0.04       99.14
            29 |          7        0.07       99.21
            30 |          6        0.06       99.27
            31 |          6        0.06       99.33
            32 |          3        0.03       99.36
            33 |         11        0.11       99.47
            34 |          8        0.08       99.55
            35 |         10        0.10       99.65
            36 |         12        0.12       99.77
            37 |          9        0.09       99.86
            38 |          4        0.04       99.90
            39 |          6        0.06       99.96
            40 |          2        0.02       99.98
            41 |          2        0.02      100.00
---------------+-----------------------------------
         Total |     10,000      100.00

by Jean Roth , jroth@nber.org , 27 Mar 2017