Frequencies for first 10,000 rows of birmon variable in natl1976 dataset :

   Month of |
      birth |      Freq.     Percent        Cum.
------------+-----------------------------------
          1 |      4,692       46.92       46.92
          2 |      3,735       37.35       84.27
          3 |      1,573       15.73      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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