Frequencies for first 10,000 rows of cityres variable in natl1974 dataset :

  NCHS City |
         of |
  Residence |      Freq.     Percent        Cum.
------------+-----------------------------------
        021 |      1,016       10.16       10.16
        066 |          1        0.01       10.17
        075 |          3        0.03       10.20
        081 |          1        0.01       10.21
        282 |          1        0.01       10.22
        291 |          2        0.02       10.24
        294 |          1        0.01       10.25
        999 |      8,974       89.74       99.99
        ZZZ |          1        0.01      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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