Frequencies for first 10,000 rows of tow_veh variable in vehicle dataset :

      TOWED |
   TRAILING |
       UNIT |      Freq.     Percent        Cum.
------------+-----------------------------------
          0 |      9,298       92.98       92.98
          1 |        527        5.27       98.25
          2 |         66        0.66       98.91
          3 |         13        0.13       99.04
          4 |          4        0.04       99.08
          9 |         92        0.92      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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