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

NCHS County |
         of |
  Occurence |      Freq.     Percent        Cum.
------------+-----------------------------------
      01008 |        270        2.70        2.70
      01028 |        264        2.64        5.34
      01037 |      2,495       24.95       30.29
      01045 |        999        9.99       40.28
      01049 |        389        3.89       44.17
      01051 |      1,262       12.62       56.79
      01063 |        374        3.74       60.53
      01999 |      3,947       39.47      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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