Frequencies for first 10,000 rows of dgestat variable in natlterr1998 dataset :

Gestation - |
  Detail in |
      Weeks |      Freq.     Percent        Cum.
------------+-----------------------------------
         22 |          2        0.02        0.02
         23 |          1        0.01        0.03
         24 |          7        0.07        0.10
         25 |         20        0.20        0.30
         26 |         16        0.16        0.46
         27 |         21        0.21        0.67
         28 |         28        0.28        0.95
         29 |         26        0.26        1.21
         30 |         38        0.38        1.59
         31 |         43        0.43        2.02
         32 |         66        0.66        2.68
         33 |         76        0.76        3.44
         34 |        147        1.47        4.91
         35 |        293        2.93        7.84
         36 |        514        5.14       12.98
         37 |      1,141       11.41       24.39
         38 |      2,039       20.39       44.78
         39 |      2,368       23.68       68.46
         40 |      2,062       20.62       89.08
         41 |        780        7.80       96.88
         42 |        215        2.15       99.03
         43 |         81        0.81       99.84
         44 |          6        0.06       99.90
         99 |         10        0.10      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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