Frequencies for first 10,000 rows of gestat10 variable in natl1998 dataset :

  Gestation |
  Recode 10 |      Freq.     Percent        Cum.
------------+-----------------------------------
          1 |          5        0.05        0.05
          2 |        100        1.00        1.05
          3 |        180        1.80        2.85
          4 |        685        6.85        9.70
          5 |        500        5.00       14.70
          6 |      4,864       48.64       63.34
          7 |      1,905       19.05       82.39
          8 |        929        9.29       91.68
          9 |        828        8.28       99.96
         10 |          4        0.04      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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