Frequencies for first 10,000 rows of gestat10 variable in natl1976 dataset :

  Gestation |
  Recode 10 |      Freq.     Percent        Cum.
------------+-----------------------------------
          1 |          3        0.03        0.03
          2 |         42        0.42        0.45
          3 |         88        0.88        1.33
          4 |        467        4.67        6.00
          5 |        254        2.54        8.54
          6 |      2,998       29.98       38.52
          7 |      1,731       17.31       55.83
          8 |      1,930       19.30       75.13
          9 |        782        7.82       82.95
         10 |      1,705       17.05      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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