Frequencies for first 10,000 rows of estgest variable in natl2004 dataset :

Obstetric/C |
    linical |
  Gestation |
   Est. U;R |      Freq.     Percent        Cum.
------------+-----------------------------------
         19 |          2        0.02        0.02
         21 |          1        0.01        0.03
         22 |          9        0.09        0.12
         23 |          6        0.06        0.18
         24 |          5        0.05        0.23
         25 |         11        0.11        0.34
         26 |         10        0.10        0.44
         27 |         10        0.10        0.54
         28 |         18        0.18        0.72
         29 |         16        0.16        0.88
         30 |         19        0.19        1.07
         31 |         24        0.24        1.31
         32 |         48        0.48        1.79
         33 |         58        0.58        2.37
         34 |        111        1.11        3.48
         35 |        166        1.66        5.14
         36 |        400        4.00        9.14
         37 |        771        7.71       16.85
         38 |      1,793       17.93       34.78
         39 |      2,722       27.22       62.00
         40 |      2,614       26.14       88.14
         41 |        988        9.88       98.02
         42 |        128        1.28       99.30
         43 |          3        0.03       99.33
         44 |          1        0.01       99.34
         99 |         66        0.66      100.00
------------+-----------------------------------
      Total |     10,000      100.00

by Jean Roth , jroth@nber.org , 21 Jan 2016