Frequencies for first 10,000 rows of estgest variable in natl2013 dataset :

Obstetric/C |
    linical |
  Gestation |
   Est. RFP |
573=f_cline |
     st U;R |      Freq.     Percent        Cum.
------------+-----------------------------------
         18 |          1        0.01        0.01
         20 |          1        0.01        0.02
         21 |          4        0.04        0.06
         22 |          5        0.05        0.11
         23 |          5        0.05        0.16
         24 |          4        0.04        0.20
         25 |          4        0.04        0.24
         26 |          7        0.07        0.31
         27 |          8        0.08        0.39
         28 |          8        0.08        0.47
         29 |         17        0.17        0.64
         30 |         24        0.24        0.88
         31 |         26        0.26        1.14
         32 |         35        0.35        1.49
         33 |         52        0.52        2.01
         34 |        115        1.15        3.16
         35 |        175        1.75        4.91
         36 |        336        3.36        8.27
         37 |        925        9.25       17.52
         38 |      1,583       15.83       33.35
         39 |      3,131       31.31       64.66
         40 |      2,432       24.32       88.98
         41 |        942        9.42       98.40
         42 |         72        0.72       99.12
         44 |          1        0.01       99.13
         47 |          1        0.01       99.14
         99 |         86        0.86      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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