Frequencies for first 10,000 rows of cityres variable in natlterr1999 dataset :

  NCHS City |
         of |
  Residence |      Freq.     Percent        Cum.
------------+-----------------------------------
        000 |          8        0.08        0.08
        999 |      9,989       99.89       99.97
        ZZZ |          3        0.03      100.00
------------+-----------------------------------
      Total |     10,000      100.00

by Jean Roth , jroth@nber.org , 22 Dec 2015