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

      TOWED |
   TRAILING |
       UNIT |      Freq.     Percent        Cum.
------------+-----------------------------------
          0 |      9,192       91.92       91.92
          1 |        651        6.51       98.43
          2 |         57        0.57       99.00
          3 |          1        0.01       99.01
          4 |          2        0.02       99.03
          9 |         97        0.97      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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