Frequencies for first 10,000 rows of birmon variable in natl1983 dataset :

   Month of |
      birth |      Freq.     Percent        Cum.
------------+-----------------------------------
          1 |      4,853       48.53       48.53
          2 |      3,783       37.83       86.36
          3 |      1,363       13.63       99.99
          4 |          1        0.01      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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