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

      TOWED |
   TRAILING |
       UNIT |      Freq.     Percent        Cum.
------------+-----------------------------------
          0 |      9,256       92.56       92.56
          1 |        635        6.35       98.91
          2 |         58        0.58       99.49
          3 |          2        0.02       99.51
          4 |          4        0.04       99.55
          9 |         45        0.45      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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