Frequencies for first 10,000 rows of estgest variable in natl2006 dataset :

Obstetric/C |
    linical |
  Gestation |
   Est. RFP |
573=f_cline |
     st U;R |      Freq.     Percent        Cum.
------------+-----------------------------------
         19 |          2        0.02        0.02
         20 |          2        0.02        0.04
         21 |          2        0.02        0.06
         22 |          2        0.02        0.08
         23 |          8        0.08        0.16
         24 |         11        0.11        0.27
         25 |          6        0.06        0.33
         26 |         10        0.10        0.43
         27 |          6        0.06        0.49
         28 |         15        0.15        0.64
         29 |         13        0.13        0.77
         30 |         19        0.19        0.96
         31 |         20        0.20        1.16
         32 |         30        0.30        1.46
         33 |         53        0.53        1.99
         34 |         94        0.94        2.93
         35 |        197        1.97        4.90
         36 |        393        3.93        8.83
         37 |        764        7.64       16.47
         38 |      1,716       17.16       33.63
         39 |      2,728       27.28       60.91
         40 |      2,796       27.96       88.87
         41 |        986        9.86       98.73
         42 |         98        0.98       99.71
         43 |          3        0.03       99.74
         44 |          1        0.01       99.75
         99 |         25        0.25      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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