Frequencies for first 10,000 rows of combgest variable in natlterr2011 dataset :

Gestation - |
  Detail in |
  Weeks U;R |      Freq.     Percent        Cum.
------------+-----------------------------------
         17 |          2        0.02        0.02
         18 |          2        0.02        0.04
         19 |          2        0.02        0.06
         20 |          3        0.03        0.09
         21 |          4        0.04        0.13
         22 |          6        0.06        0.19
         23 |          6        0.06        0.25
         24 |         12        0.12        0.37
         25 |         15        0.15        0.52
         26 |         16        0.16        0.68
         27 |         17        0.17        0.85
         28 |         19        0.19        1.04
         29 |         21        0.21        1.25
         30 |         27        0.27        1.52
         31 |         58        0.58        2.10
         32 |         62        0.62        2.72
         33 |        103        1.03        3.75
         34 |        165        1.65        5.40
         35 |        249        2.49        7.89
         36 |        531        5.31       13.20
         37 |      1,072       10.72       23.92
         38 |      2,015       20.15       44.07
         39 |      2,148       21.48       65.55
         40 |      1,310       13.10       78.65
         41 |        479        4.79       83.44
         42 |        164        1.64       85.08
         43 |         89        0.89       85.97
         44 |         57        0.57       86.54
         45 |         30        0.30       86.84
         46 |         13        0.13       86.97
         47 |         10        0.10       87.07
         99 |      1,293       12.93      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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