Frequencies for first 10,000 rows of fed_aid variable in accident dataset :

Federal-Aid |
     System |      Freq.     Percent        Cum.
------------+-----------------------------------
          1 |      1,192       11.92       11.92
          2 |      2,978       29.78       41.70
          3 |      2,559       25.59       67.29
          4 |        975        9.75       77.04
          5 |      2,296       22.96      100.00
------------+-----------------------------------
      Total |     10,000      100.00

by Jean Roth , jroth@nber.org , 18 Apr 2016