Frequencies for first 10,000 rows of estgest variable in natlterr2008 dataset :

Obstetric/C |
    linical |
  Gestation |
   Est. RFP |
573=f_cline |
     st U;R |      Freq.     Percent        Cum.
------------+-----------------------------------
         18 |          1        0.01        0.01
         20 |          2        0.02        0.03
         22 |          4        0.04        0.07
         23 |          2        0.02        0.09
         24 |         15        0.15        0.24
         25 |          8        0.08        0.32
         26 |          3        0.03        0.35
         27 |          9        0.09        0.44
         28 |         14        0.14        0.58
         29 |         17        0.17        0.75
         30 |         32        0.32        1.07
         31 |         36        0.36        1.43
         32 |         55        0.55        1.98
         33 |         75        0.75        2.73
         34 |        165        1.65        4.38
         35 |        235        2.35        6.73
         36 |        504        5.04       11.77
         37 |      1,120       11.20       22.97
         38 |      2,136       21.36       44.33
         39 |      2,127       21.27       65.60
         40 |      1,458       14.58       80.18
         41 |        459        4.59       84.77
         42 |        111        1.11       85.88
         43 |         40        0.40       86.28
         44 |         13        0.13       86.41
         45 |          5        0.05       86.46
         99 |      1,354       13.54      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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