Frequencies for first 10,000 rows of birmon variable in natl1999 dataset :

   Month of |
      Birth |      Freq.     Percent        Cum.
------------+-----------------------------------
          1 |      5,003       50.03       50.03
          2 |      4,390       43.90       93.93
          3 |        607        6.07      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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