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

Federal-Aid |
     System |      Freq.     Percent        Cum.
------------+-----------------------------------
          1 |      1,006       10.06       10.06
          2 |      2,996       29.96       40.02
          3 |        816        8.16       48.18
          4 |      2,197       21.97       70.15
          5 |        230        2.30       72.45
          6 |        122        1.22       73.67
          7 |        745        7.45       81.12
          8 |      1,876       18.76       99.88
          9 |         12        0.12      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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