Frequencies for first 10,000 rows of ocntyfips variable in natlterr2008 dataset :

 Occurrence |
FIPS County |
        U;R |      Freq.     Percent        Cum.
------------+-----------------------------------
          0 |      2,597       25.97       25.97
         10 |      3,464       34.64       60.61
         21 |        443        4.43       65.04
         25 |        269        2.69       67.73
         31 |        108        1.08       68.81
         97 |        245        2.45       71.26
        113 |        507        5.07       76.33
        127 |      1,064       10.64       86.97
        999 |      1,303       13.03      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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