Frequencies for first 10,000 rows of quarter variable in sdued1991 dataset :

    Quarter |      Freq.     Percent        Cum.
------------+-----------------------------------
          1 |      4,252       42.52       42.52
          2 |      4,894       48.94       91.46
          3 |        854        8.54      100.00
------------+-----------------------------------
      Total |     10,000      100.00

by Jean Roth , jroth@nber.org , 20 Feb 2018