Frequencies for first 10,000 rows of agi_class variable in zipcode2006 dataset :

  agi_class |      Freq.     Percent        Cum.
------------+-----------------------------------
          1 |      1,429       14.29       14.29
          2 |      1,429       14.29       28.58
          3 |      1,429       14.29       42.87
          4 |      1,429       14.29       57.16
          5 |      1,428       14.28       71.44
          6 |      1,428       14.28       85.72
          7 |      1,428       14.28      100.00
------------+-----------------------------------
      Total |     10,000      100.00

by Jean Roth , jroth@nber.org , 20 Jun 2017