Frequencies for first 10,000 rows of dgestat variable in natlterr1996 dataset :

Gestation - |
  Detail in |
      Weeks |      Freq.     Percent        Cum.
------------+-----------------------------------
         21 |          3        0.03        0.03
         22 |          3        0.03        0.06
         23 |          3        0.03        0.09
         24 |          1        0.01        0.10
         25 |          8        0.08        0.18
         26 |         10        0.10        0.28
         27 |         17        0.17        0.45
         28 |         19        0.19        0.64
         29 |         19        0.19        0.83
         30 |         27        0.27        1.10
         31 |         29        0.29        1.39
         32 |         57        0.57        1.96
         33 |         85        0.85        2.81
         34 |        162        1.62        4.43
         35 |        238        2.38        6.81
         36 |        477        4.77       11.58
         37 |        956        9.56       21.14
         38 |      1,819       18.19       39.33
         39 |      2,426       24.26       63.59
         40 |      2,326       23.26       86.85
         41 |        944        9.44       96.29
         42 |        290        2.90       99.19
         43 |         74        0.74       99.93
         44 |          3        0.03       99.96
         99 |          4        0.04      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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