Frequencies for first 10,000 rows of gestat10 variable in natl1977 dataset :

  Gestation |
  Recode 10 |      Freq.     Percent        Cum.
------------+-----------------------------------
          1 |          6        0.06        0.06
          2 |         47        0.47        0.53
          3 |        107        1.07        1.60
          4 |        433        4.33        5.93
          5 |        274        2.74        8.67
          6 |      2,903       29.03       37.70
          7 |      1,756       17.56       55.26
          8 |      1,906       19.06       74.32
          9 |        741        7.41       81.73
         10 |      1,827       18.27      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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