Frequencies for first 10,000 rows of clingest variable in natlterr1998 dataset :

   Clinical |
Estimate of |
  Gestation |      Freq.     Percent        Cum.
------------+-----------------------------------
         22 |          2        0.02        0.02
         23 |          3        0.03        0.05
         24 |          5        0.05        0.10
         25 |         11        0.11        0.21
         26 |         19        0.19        0.40
         27 |         15        0.15        0.55
         28 |         24        0.24        0.79
         29 |         28        0.28        1.07
         30 |         26        0.26        1.33
         31 |         26        0.26        1.59
         32 |         52        0.52        2.11
         33 |         53        0.53        2.64
         34 |         91        0.91        3.55
         35 |        210        2.10        5.65
         36 |        434        4.34        9.99
         37 |        990        9.90       19.89
         38 |      2,048       20.48       40.37
         39 |      2,352       23.52       63.89
         40 |      2,624       26.24       90.13
         41 |        776        7.76       97.89
         42 |        184        1.84       99.73
         43 |          7        0.07       99.80
         99 |         20        0.20      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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