Frequencies for first 10,000 rows of birmon variable in natl1986 dataset :

   Month of |
      birth |      Freq.     Percent        Cum.
------------+-----------------------------------
          1 |      4,837       48.37       48.37
          2 |      3,469       34.69       83.06
          3 |      1,693       16.93       99.99
         12 |          1        0.01      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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