Frequencies for first 10,000 rows of dgestat variable in natlterr2002 dataset :

Gestation - |
  Detail in |
      Weeks |      Freq.     Percent        Cum.
------------+-----------------------------------
         23 |         15        0.15        0.15
         24 |          9        0.09        0.24
         25 |         11        0.11        0.35
         26 |         17        0.17        0.52
         27 |         10        0.10        0.62
         28 |         17        0.17        0.79
         29 |         17        0.17        0.96
         30 |         33        0.33        1.29
         31 |         43        0.43        1.72
         32 |         83        0.83        2.55
         33 |        102        1.02        3.57
         34 |        202        2.02        5.59
         35 |        342        3.42        9.01
         36 |        760        7.60       16.61
         37 |      1,751       17.51       34.12
         38 |      2,508       25.08       59.20
         39 |      2,223       22.23       81.43
         40 |      1,376       13.76       95.19
         41 |        326        3.26       98.45
         42 |        106        1.06       99.51
         43 |         42        0.42       99.93
         44 |          4        0.04       99.97
         99 |          3        0.03      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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