Frequencies for first 10,000 rows of cityres variable in natl1990 dataset :

  NCHS City |
         of |
  Residence |      Freq.     Percent        Cum.
------------+-----------------------------------
        008 |        849        8.49        8.49
        010 |          1        0.01        8.50
        021 |        546        5.46       13.96
        023 |        179        1.79       15.75
        024 |        745        7.45       23.20
        031 |          1        0.01       23.21
        033 |          2        0.02       23.23
        999 |      7,675       76.75       99.98
        ZZZ |          2        0.02      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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