Frequencies for first 10,000 rows of cntocpop variable in natl1997 dataset :

 Population |
    Size of |
  County of |
 Occurrence |      Freq.     Percent        Cum.
------------+-----------------------------------
          1 |      2,445       24.45       24.45
          2 |      1,235       12.35       36.80
          3 |      2,833       28.33       65.13
          9 |      3,487       34.87      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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