Frequencies for first 10,000 rows of birmon variable in natl1989 dataset :

   Month of |
      Birth |      Freq.     Percent        Cum.
------------+-----------------------------------
          1 |      4,855       48.55       48.55
          2 |      3,834       38.34       86.89
          3 |      1,303       13.03       99.92
          4 |          7        0.07       99.99
          7 |          1        0.01      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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