Frequencies for first 10,000 rows of birmon variable in natl1997 dataset :

   Month of |
      Birth |      Freq.     Percent        Cum.
------------+-----------------------------------
          1 |      5,074       50.74       50.74
          2 |      4,309       43.09       93.83
          3 |        617        6.17      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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