Frequencies for first 10,000 rows of gestwk variable in namcs2005 dataset :

       week of |
     gestation |      Freq.     Percent        Cum.
---------------+-----------------------------------
             5 |          1        0.01        0.01
             6 |          4        0.04        0.05
             7 |          1        0.01        0.06
             8 |          4        0.04        0.10
             9 |          2        0.02        0.12
            11 |          1        0.01        0.13
            12 |          2        0.02        0.15
            13 |          1        0.01        0.16
            14 |          2        0.02        0.18
            15 |          3        0.03        0.21
            16 |          2        0.02        0.23
            17 |          1        0.01        0.24
            18 |          2        0.02        0.26
            19 |          1        0.01        0.27
            20 |          3        0.03        0.30
            21 |          1        0.01        0.31
            22 |          1        0.01        0.32
            23 |          1        0.01        0.33
            24 |          1        0.01        0.34
            26 |          2        0.02        0.36
            28 |          1        0.01        0.37
            30 |          1        0.01        0.38
            32 |          3        0.03        0.41
            34 |          1        0.01        0.42
            35 |          1        0.01        0.43
            37 |          1        0.01        0.44
            38 |          1        0.01        0.45
            39 |          2        0.02        0.47
            40 |          1        0.01        0.48
            41 |          1        0.01        0.49
Not applicable |      9,340       93.40       93.89
         Blank |        611        6.11      100.00
---------------+-----------------------------------
         Total |     10,000      100.00

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