Frequencies for first 10,000 rows of ocntyfips variable in natlterr2005 dataset :

 Occurrence |
FIPS County |
        U;R |      Freq.     Percent        Cum.
------------+-----------------------------------
          0 |      3,053       30.53       30.53
         10 |      3,202       32.02       62.55
         21 |        473        4.73       67.28
         25 |        253        2.53       69.81
         31 |         83        0.83       70.64
         97 |        207        2.07       72.71
        113 |        496        4.96       77.67
        127 |      1,026       10.26       87.93
        999 |      1,207       12.07      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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