Frequencies for first 10,000 rows of gestat10 variable in natl1979 dataset :

  Gestation |
  Recode 10 |      Freq.     Percent        Cum.
------------+-----------------------------------
          2 |         53        0.53        0.53
          3 |        104        1.04        1.57
          4 |        447        4.47        6.04
          5 |        267        2.67        8.71
          6 |      2,822       28.22       36.93
          7 |      1,653       16.53       53.46
          8 |      1,257       12.57       66.03
          9 |      1,481       14.81       80.84
         10 |      1,916       19.16      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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