Frequencies for first 10,000 rows of combgest variable in natl2017 dataset :

   Combined |
  Gestation |
  -- Detail |
   in Weeks |
 17-47 17th |
    through |
  47th week |
         of |      Freq.     Percent        Cum.
------------+-----------------------------------
         19 |          3        0.03        0.03
         20 |          3        0.03        0.06
         21 |          1        0.01        0.07
         22 |          4        0.04        0.11
         23 |          1        0.01        0.12
         24 |          6        0.06        0.18
         25 |          8        0.08        0.26
         26 |         14        0.14        0.40
         27 |          9        0.09        0.49
         28 |         28        0.28        0.77
         29 |         15        0.15        0.92
         30 |         27        0.27        1.19
         31 |         32        0.32        1.51
         32 |         67        0.67        2.18
         33 |         75        0.75        2.93
         34 |        135        1.35        4.28
         35 |        217        2.17        6.45
         36 |        396        3.96       10.41
         37 |        939        9.39       19.80
         38 |      1,479       14.79       34.59
         39 |      2,666       26.66       61.25
         40 |      2,065       20.65       81.90
         41 |      1,226       12.26       94.16
         42 |        311        3.11       97.27
         43 |        123        1.23       98.50
         44 |         71        0.71       99.21
         45 |         43        0.43       99.64
         46 |         22        0.22       99.86
         47 |          9        0.09       99.95
         99 |          5        0.05      100.00
------------+-----------------------------------
      Total |     10,000      100.00

by Jean Roth , jroth@nber.org , 19 Sep 2018