Frequencies for first 10,000 rows of gestat10 variable in natl1980 dataset :

  Gestation |
  Recode 10 |      Freq.     Percent        Cum.
------------+-----------------------------------
          1 |          6        0.06        0.06
          2 |         45        0.45        0.51
          3 |        111        1.11        1.62
          4 |        407        4.07        5.69
          5 |        283        2.83        8.52
          6 |      2,872       28.72       37.24
          7 |      1,766       17.66       54.90
          8 |      1,183       11.83       66.73
          9 |      1,405       14.05       80.78
         10 |      1,922       19.22      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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