Frequencies for first 10,000 rows of combgest variable in natl2003 dataset :

Gestation - |
  Detail in |
  Weeks U;R |      Freq.     Percent        Cum.
------------+-----------------------------------
         21 |          1        0.01        0.01
         22 |          5        0.05        0.06
         23 |          6        0.06        0.12
         24 |          5        0.05        0.17
         25 |         10        0.10        0.27
         26 |          5        0.05        0.32
         27 |          8        0.08        0.40
         28 |         17        0.17        0.57
         29 |         20        0.20        0.77
         30 |         22        0.22        0.99
         31 |         29        0.29        1.28
         32 |         43        0.43        1.71
         33 |         67        0.67        2.38
         34 |        133        1.33        3.71
         35 |        240        2.40        6.11
         36 |        464        4.64       10.75
         37 |        814        8.14       18.89
         38 |      1,816       18.16       37.05
         39 |      2,487       24.87       61.92
         40 |      2,178       21.78       83.70
         41 |      1,025       10.25       93.95
         42 |        303        3.03       96.98
         43 |        121        1.21       98.19
         44 |         45        0.45       98.64
         45 |         24        0.24       98.88
         46 |         18        0.18       99.06
         47 |         10        0.10       99.16
         99 |         84        0.84      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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