Frequencies for first 10,000 rows of clingest variable in natlterr2000 dataset :

   Clinical |
Estimate of |
  Gestation |      Freq.     Percent        Cum.
------------+-----------------------------------
         20 |          1        0.01        0.01
         21 |          2        0.02        0.03
         22 |          1        0.01        0.04
         23 |          3        0.03        0.07
         24 |          8        0.08        0.15
         25 |          8        0.08        0.23
         26 |         17        0.17        0.40
         27 |         18        0.18        0.58
         28 |         21        0.21        0.79
         29 |         18        0.18        0.97
         30 |         28        0.28        1.25
         31 |         27        0.27        1.52
         32 |         54        0.54        2.06
         33 |         73        0.73        2.79
         34 |        146        1.46        4.25
         35 |        226        2.26        6.51
         36 |        482        4.82       11.33
         37 |      1,139       11.39       22.72
         38 |      2,367       23.67       46.39
         39 |      2,438       24.38       70.77
         40 |      2,384       23.84       94.61
         41 |        451        4.51       99.12
         42 |         74        0.74       99.86
         43 |          6        0.06       99.92
         99 |          8        0.08      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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