Frequencies for first 10,000 rows of ocntyfips variable in natlterr2007 dataset :

 Occurrence |
FIPS County |
        U;R |      Freq.     Percent        Cum.
------------+-----------------------------------
          0 |      2,672       26.72       26.72
         10 |      3,491       34.91       61.63
         21 |        400        4.00       65.63
         25 |        241        2.41       68.04
         31 |         95        0.95       68.99
         97 |        249        2.49       71.48
        113 |        497        4.97       76.45
        127 |      1,118       11.18       87.63
        999 |      1,237       12.37      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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