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

      TOWED |
   TRAILING |
       UNIT |      Freq.     Percent        Cum.
------------+-----------------------------------
          0 |      9,336       93.36       93.36
          1 |        531        5.31       98.67
          2 |         69        0.69       99.36
          3 |          6        0.06       99.42
          4 |          1        0.01       99.43
          9 |         57        0.57      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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