Frequencies for first 10,000 rows of gestat10 variable in natl1978 dataset :

  Gestation |
  Recode 10 |      Freq.     Percent        Cum.
------------+-----------------------------------
          1 |          5        0.05        0.05
          2 |         40        0.40        0.45
          3 |        102        1.02        1.47
          4 |        399        3.99        5.46
          5 |        316        3.16        8.62
          6 |      2,851       28.51       37.13
          7 |      1,642       16.42       53.55
          8 |      1,844       18.44       71.99
          9 |        800        8.00       79.99
         10 |      2,001       20.01      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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