Frequencies for first 10,000 rows of combgest variable in natlterr2007 dataset :

Gestation - |
  Detail in |
  Weeks U;R |      Freq.     Percent        Cum.
------------+-----------------------------------
         18 |          1        0.01        0.01
         19 |          1        0.01        0.02
         21 |          3        0.03        0.05
         22 |          4        0.04        0.09
         23 |          6        0.06        0.15
         24 |         10        0.10        0.25
         25 |          9        0.09        0.34
         26 |         12        0.12        0.46
         27 |         18        0.18        0.64
         28 |         17        0.17        0.81
         29 |         33        0.33        1.14
         30 |         37        0.37        1.51
         31 |         43        0.43        1.94
         32 |         72        0.72        2.66
         33 |        117        1.17        3.83
         34 |        203        2.03        5.86
         35 |        290        2.90        8.76
         36 |        573        5.73       14.49
         37 |      1,118       11.18       25.67
         38 |      1,856       18.56       44.23
         39 |      1,875       18.75       62.98
         40 |      1,267       12.67       75.65
         41 |        525        5.25       80.90
         42 |        241        2.41       83.31
         43 |        148        1.48       84.79
         44 |         92        0.92       85.71
         45 |         49        0.49       86.20
         46 |         25        0.25       86.45
         47 |         25        0.25       86.70
         99 |      1,330       13.30      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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