Frequencies for first 10,000 rows of birmon variable in natl1974 dataset :

   Month of |
      birth |      Freq.     Percent        Cum.
------------+-----------------------------------
          1 |      2,530       25.30       25.30
          2 |      2,257       22.57       47.87
          3 |      2,322       23.22       71.09
          4 |      2,010       20.10       91.19
          5 |        876        8.76       99.95
          6 |          2        0.02       99.97
          7 |          3        0.03      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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