Frequencies for first 10,000 rows of ocntyfips variable in natlterr2010 dataset :

 Occurrence |
FIPS County |
        U;R |      Freq.     Percent        Cum.
------------+-----------------------------------
          0 |      2,305       23.05       23.05
         10 |      3,422       34.22       57.27
         21 |        442        4.42       61.69
         25 |        255        2.55       64.24
         31 |         90        0.90       65.14
         97 |        328        3.28       68.42
        113 |        550        5.50       73.92
        127 |      1,188       11.88       85.80
        999 |      1,420       14.20      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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