Frequencies for first 10,000 rows of estgest variable in natl2009 dataset :

Obstetric/C |
    linical |
  Gestation |
   Est. RFP |
573=f_cline |
     st U;R |      Freq.     Percent        Cum.
------------+-----------------------------------
         18 |          1        0.01        0.01
         19 |          3        0.03        0.04
         20 |          1        0.01        0.05
         21 |          3        0.03        0.08
         22 |          3        0.03        0.11
         23 |          7        0.07        0.18
         24 |         12        0.12        0.30
         25 |         10        0.10        0.40
         26 |          9        0.09        0.49
         27 |         10        0.10        0.59
         28 |         20        0.20        0.79
         29 |         23        0.23        1.02
         30 |         25        0.25        1.27
         31 |         38        0.38        1.65
         32 |         46        0.46        2.11
         33 |         62        0.62        2.73
         34 |        126        1.26        3.99
         35 |        211        2.11        6.10
         36 |        453        4.53       10.63
         37 |        926        9.26       19.89
         38 |      2,205       22.05       41.94
         39 |      3,508       35.08       77.02
         40 |      1,828       18.28       95.30
         41 |        429        4.29       99.59
         42 |         34        0.34       99.93
         43 |          2        0.02       99.95
         99 |          5        0.05      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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