Frequencies for first 10,000 rows of combgest variable in natlterr2010 dataset :

Gestation - |
  Detail in |
  Weeks U;R |      Freq.     Percent        Cum.
------------+-----------------------------------
         17 |          1        0.01        0.01
         20 |          2        0.02        0.03
         21 |          1        0.01        0.04
         22 |          3        0.03        0.07
         23 |          6        0.06        0.13
         24 |          6        0.06        0.19
         25 |         10        0.10        0.29
         26 |         12        0.12        0.41
         27 |         14        0.14        0.55
         28 |         24        0.24        0.79
         29 |         24        0.24        1.03
         30 |         29        0.29        1.32
         31 |         52        0.52        1.84
         32 |         69        0.69        2.53
         33 |        101        1.01        3.54
         34 |        174        1.74        5.28
         35 |        286        2.86        8.14
         36 |        533        5.33       13.47
         37 |      1,214       12.14       25.61
         38 |      1,936       19.36       44.97
         39 |      1,985       19.85       64.82
         40 |      1,227       12.27       77.09
         41 |        511        5.11       82.20
         42 |        216        2.16       84.36
         43 |        131        1.31       85.67
         44 |         75        0.75       86.42
         45 |         43        0.43       86.85
         46 |         20        0.20       87.05
         47 |         13        0.13       87.18
         99 |      1,282       12.82      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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