Frequencies for first 10,000 rows of gestat10 variable in natl1991 dataset :

  Gestation |
  Recode 10 |      Freq.     Percent        Cum.
------------+-----------------------------------
          1 |          2        0.02        0.02
          2 |         93        0.93        0.95
          3 |        142        1.42        2.37
          4 |        614        6.14        8.51
          5 |        386        3.86       12.37
          6 |      3,994       39.94       52.31
          7 |      2,080       20.80       73.11
          8 |      1,396       13.96       87.07
          9 |      1,278       12.78       99.85
         10 |         15        0.15      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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