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

 Population |
    Size of |
  County of |
 Occurrence |      Freq.     Percent        Cum.
------------+-----------------------------------
          1 |      2,495       24.95       24.95
          2 |        389        3.89       28.84
          3 |      3,169       31.69       60.53
          9 |      3,947       39.47      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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