Frequencies for first 10,000 rows of estgest variable in natl2007 dataset :

Obstetric/C |
    linical |
  Gestation |
   Est. RFP |
573=f_cline |
     st U;R |      Freq.     Percent        Cum.
------------+-----------------------------------
         18 |          1        0.01        0.01
         19 |          1        0.01        0.02
         20 |          1        0.01        0.03
         21 |          4        0.04        0.07
         22 |          7        0.07        0.14
         23 |          6        0.06        0.20
         24 |          7        0.07        0.27
         25 |          2        0.02        0.29
         26 |          9        0.09        0.38
         27 |         13        0.13        0.51
         28 |         12        0.12        0.63
         29 |         14        0.14        0.77
         30 |         20        0.20        0.97
         31 |         27        0.27        1.24
         32 |         33        0.33        1.57
         33 |         60        0.60        2.17
         34 |        122        1.22        3.39
         35 |        167        1.67        5.06
         36 |        365        3.65        8.71
         37 |        797        7.97       16.68
         38 |      1,800       18.00       34.68
         39 |      2,673       26.73       61.41
         40 |      2,752       27.52       88.93
         41 |        984        9.84       98.77
         42 |         93        0.93       99.70
         43 |          1        0.01       99.71
         47 |          1        0.01       99.72
         99 |         28        0.28      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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