Frequencies for first 10,000 rows of combgest variable in natl2005 dataset :

Gestation - |
  Detail in |
  Weeks U;R |      Freq.     Percent        Cum.
------------+-----------------------------------
         17 |          1        0.01        0.01
         18 |          2        0.02        0.03
         19 |          1        0.01        0.04
         21 |          2        0.02        0.06
         22 |          4        0.04        0.10
         23 |          8        0.08        0.18
         24 |          5        0.05        0.23
         25 |          2        0.02        0.25
         26 |          8        0.08        0.33
         27 |          5        0.05        0.38
         28 |         20        0.20        0.58
         29 |         14        0.14        0.72
         30 |         25        0.25        0.97
         31 |         26        0.26        1.23
         32 |         28        0.28        1.51
         33 |         78        0.78        2.29
         34 |        136        1.36        3.65
         35 |        248        2.48        6.13
         36 |        425        4.25       10.38
         37 |        903        9.03       19.41
         38 |      1,779       17.79       37.20
         39 |      2,586       25.86       63.06
         40 |      2,167       21.67       84.73
         41 |      1,019       10.19       94.92
         42 |        285        2.85       97.77
         43 |        103        1.03       98.80
         44 |         50        0.50       99.30
         45 |         32        0.32       99.62
         46 |         15        0.15       99.77
         47 |          9        0.09       99.86
         99 |         14        0.14      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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