Frequencies for first 10,000 rows of combgest variable in natlterr2012 dataset :

Gestation - |
  Detail in |
  Weeks U;R |      Freq.     Percent        Cum.
------------+-----------------------------------
         18 |          2        0.02        0.02
         19 |          1        0.01        0.03
         20 |          1        0.01        0.04
         21 |          3        0.03        0.07
         22 |          2        0.02        0.09
         23 |          3        0.03        0.12
         24 |          8        0.08        0.20
         25 |         13        0.13        0.33
         26 |         10        0.10        0.43
         27 |          9        0.09        0.52
         28 |         21        0.21        0.73
         29 |         25        0.25        0.98
         30 |         31        0.31        1.29
         31 |         35        0.35        1.64
         32 |         84        0.84        2.48
         33 |        100        1.00        3.48
         34 |        150        1.50        4.98
         35 |        287        2.87        7.85
         36 |        495        4.95       12.80
         37 |      1,045       10.45       23.25
         38 |      1,863       18.63       41.88
         39 |      2,183       21.83       63.71
         40 |      1,348       13.48       77.19
         41 |        519        5.19       82.38
         42 |        203        2.03       84.41
         43 |        140        1.40       85.81
         44 |         77        0.77       86.58
         45 |         33        0.33       86.91
         46 |         22        0.22       87.13
         47 |         15        0.15       87.28
         99 |      1,272       12.72      100.00
------------+-----------------------------------
      Total |     10,000      100.00

by Jean Roth , jroth@nber.org , 5 May 2016