Frequencies for first 10,000 rows of estgest variable in natlterr2012 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
         21 |          1        0.01        0.04
         22 |          1        0.01        0.05
         23 |          3        0.03        0.08
         24 |         11        0.11        0.19
         25 |         12        0.12        0.31
         26 |          8        0.08        0.39
         27 |          2        0.02        0.41
         28 |          7        0.07        0.48
         29 |          9        0.09        0.57
         30 |         26        0.26        0.83
         31 |         24        0.24        1.07
         32 |         41        0.41        1.48
         33 |         57        0.57        2.05
         34 |        100        1.00        3.05
         35 |        208        2.08        5.13
         36 |        412        4.12        9.25
         37 |      1,118       11.18       20.43
         38 |      2,300       23.00       43.43
         39 |      2,458       24.58       68.01
         40 |      1,472       14.72       82.73
         41 |        328        3.28       86.01
         42 |         42        0.42       86.43
         43 |          4        0.04       86.47
         44 |          1        0.01       86.48
         99 |      1,352       13.52      100.00
------------+-----------------------------------
      Total |     10,000      100.00

by Jean Roth , jroth@nber.org , 5 May 2016