Frequencies for first 10,000 rows of cntocpop variable in natl1991 dataset :

 Population |
    Size of |
  County of |
 Occurrence |      Freq.     Percent        Cum.
------------+-----------------------------------
          1 |      2,818       28.18       28.18
          2 |        224        2.24       30.42
          3 |      3,007       30.07       60.49
          9 |      3,951       39.51      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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