Frequencies for first 10,000 rows of gestat10 variable in natl1990 dataset :

  Gestation |
  Recode 10 |      Freq.     Percent        Cum.
------------+-----------------------------------
          1 |          2        0.02        0.02
          2 |         74        0.74        0.76
          3 |        158        1.58        2.34
          4 |        682        6.82        9.16
          5 |        371        3.71       12.87
          6 |      4,140       41.40       54.27
          7 |      2,058       20.58       74.85
          8 |      1,293       12.93       87.78
          9 |      1,203       12.03       99.81
         10 |         19        0.19      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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