Frequencies for first 10,000 rows of clingest variable in natlterr1997 dataset :

   Clinical |
Estimate of |
  Gestation |      Freq.     Percent        Cum.
------------+-----------------------------------
         20 |          1        0.01        0.01
         22 |          5        0.05        0.06
         23 |          3        0.03        0.09
         24 |          5        0.05        0.14
         25 |          7        0.07        0.21
         26 |         17        0.17        0.38
         27 |         16        0.16        0.54
         28 |         15        0.15        0.69
         29 |         17        0.17        0.86
         30 |         17        0.17        1.03
         31 |         26        0.26        1.29
         32 |         43        0.43        1.72
         33 |         61        0.61        2.33
         34 |        110        1.10        3.43
         35 |        183        1.83        5.26
         36 |        392        3.92        9.18
         37 |        843        8.43       17.61
         38 |      1,865       18.65       36.26
         39 |      2,363       23.63       59.89
         40 |      2,957       29.57       89.46
         41 |        815        8.15       97.61
         42 |        221        2.21       99.82
         43 |         10        0.10       99.92
         99 |          8        0.08      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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