Frequencies for first 10,000 rows of dgestat variable in natl1990 dataset :

Gestation - |
  Detail in |
      Weeks |      Freq.     Percent        Cum.
------------+-----------------------------------
         18 |          1        0.01        0.01
         19 |          1        0.01        0.02
         20 |          1        0.01        0.03
         21 |          2        0.02        0.05
         22 |          5        0.05        0.10
         23 |         17        0.17        0.27
         24 |         10        0.10        0.37
         25 |         11        0.11        0.48
         26 |         16        0.16        0.64
         27 |         12        0.12        0.76
         28 |         23        0.23        0.99
         29 |         24        0.24        1.23
         30 |         47        0.47        1.70
         31 |         64        0.64        2.34
         32 |         78        0.78        3.12
         33 |        118        1.18        4.30
         34 |        188        1.88        6.18
         35 |        298        2.98        9.16
         36 |        371        3.71       12.87
         37 |        706        7.06       19.93
         38 |      1,307       13.07       33.00
         39 |      2,127       21.27       54.27
         40 |      2,058       20.58       74.85
         41 |      1,293       12.93       87.78
         42 |        544        5.44       93.22
         43 |        299        2.99       96.21
         44 |        163        1.63       97.84
         45 |        108        1.08       98.92
         46 |         62        0.62       99.54
         47 |         27        0.27       99.81
         99 |         19        0.19      100.00
------------+-----------------------------------
      Total |     10,000      100.00

by Jean Roth , jroth@nber.org , 3 Jan 2016