Frequencies for tow_veh variable in vehnit dataset :

      TOWED |
   TRAILING |
       UNIT |      Freq.     Percent        Cum.
------------+-----------------------------------
          0 |      1,318       88.99       88.99
          1 |        142        9.59       98.58
          2 |          8        0.54       99.12
          5 |          1        0.07       99.19
          9 |         12        0.81      100.00
------------+-----------------------------------
      Total |      1,481      100.00

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