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

      TOWED |
   TRAILING |
       UNIT |      Freq.     Percent        Cum.
------------+-----------------------------------
          0 |      9,292       92.92       92.92
          1 |        582        5.82       98.74
          2 |         52        0.52       99.26
          3 |          1        0.01       99.27
          4 |          4        0.04       99.31
          5 |          6        0.06       99.37
          9 |         63        0.63      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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