Frequencies for first 10,000 rows of clingest variable in natl1989 dataset :

   Clinical |
Estimate of |
  Gestation |      Freq.     Percent        Cum.
------------+-----------------------------------
         18 |          1        0.01        0.01
         19 |          2        0.02        0.03
         20 |          4        0.04        0.07
         21 |          2        0.02        0.09
         22 |          3        0.03        0.12
         23 |          6        0.06        0.18
         24 |         10        0.10        0.28
         25 |          4        0.04        0.32
         26 |         11        0.11        0.43
         27 |         17        0.17        0.60
         28 |         24        0.24        0.84
         29 |         16        0.16        1.00
         30 |         44        0.44        1.44
         31 |         29        0.29        1.73
         32 |         52        0.52        2.25
         33 |         62        0.62        2.87
         34 |         97        0.97        3.84
         35 |        127        1.27        5.11
         36 |        315        3.15        8.26
         37 |        546        5.46       13.72
         38 |      1,255       12.55       26.27
         39 |      1,820       18.20       44.47
         40 |      3,864       38.64       83.11
         41 |      1,053       10.53       93.64
         42 |        464        4.64       98.28
         43 |         47        0.47       98.75
         44 |          8        0.08       98.83
         46 |          1        0.01       98.84
         47 |          1        0.01       98.85
         99 |        115        1.15      100.00
------------+-----------------------------------
      Total |     10,000      100.00

by Jean Roth , jroth@nber.org , 3 Jan 2016