Frequencies for first 10,000 rows of dgestat variable in natlterr1994 dataset :

Gestation - |
  Detail in |
      Weeks |      Freq.     Percent        Cum.
------------+-----------------------------------
         21 |          2        0.02        0.02
         22 |          2        0.02        0.04
         23 |          9        0.09        0.13
         24 |          8        0.08        0.21
         25 |         10        0.10        0.31
         26 |         18        0.18        0.49
         27 |         23        0.23        0.72
         28 |         15        0.15        0.87
         29 |         28        0.28        1.15
         30 |         31        0.31        1.46
         31 |         37        0.37        1.83
         32 |         56        0.56        2.39
         33 |         83        0.83        3.22
         34 |        132        1.32        4.54
         35 |        233        2.33        6.87
         36 |        470        4.70       11.57
         37 |        922        9.22       20.79
         38 |      1,727       17.27       38.06
         39 |      2,417       24.17       62.23
         40 |      2,286       22.86       85.09
         41 |        966        9.66       94.75
         42 |        373        3.73       98.48
         43 |        130        1.30       99.78
         44 |         10        0.10       99.88
         46 |          1        0.01       99.89
         47 |          1        0.01       99.90
         99 |         10        0.10      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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