Frequencies for first 10,000 rows of combgest variable in natlterr2008 dataset :

Gestation - |
  Detail in |
  Weeks U;R |      Freq.     Percent        Cum.
------------+-----------------------------------
         18 |          1        0.01        0.01
         20 |          3        0.03        0.04
         21 |          3        0.03        0.07
         22 |          4        0.04        0.11
         23 |          2        0.02        0.13
         24 |         15        0.15        0.28
         25 |          7        0.07        0.35
         26 |          5        0.05        0.40
         27 |          8        0.08        0.48
         28 |         11        0.11        0.59
         29 |         26        0.26        0.85
         30 |         35        0.35        1.20
         31 |         53        0.53        1.73
         32 |         77        0.77        2.50
         33 |        115        1.15        3.65
         34 |        225        2.25        5.90
         35 |        307        3.07        8.97
         36 |        556        5.56       14.53
         37 |      1,065       10.65       25.18
         38 |      1,853       18.53       43.71
         39 |      1,898       18.98       62.69
         40 |      1,251       12.51       75.20
         41 |        567        5.67       80.87
         42 |        243        2.43       83.30
         43 |        152        1.52       84.82
         44 |         90        0.90       85.72
         45 |         43        0.43       86.15
         46 |         27        0.27       86.42
         47 |         12        0.12       86.54
         99 |      1,346       13.46      100.00
------------+-----------------------------------
      Total |     10,000      100.00

by Jean Roth , jroth@nber.org , 3 May 2016