Frequencies for first 10,000 rows of birmon variable in natl1990 dataset :

   Month of |
      Birth |      Freq.     Percent        Cum.
------------+-----------------------------------
          1 |      4,748       47.48       47.48
          2 |      3,716       37.16       84.64
          3 |      1,536       15.36      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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