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

      TOWED |
   TRAILING |
       UNIT |      Freq.     Percent        Cum.
------------+-----------------------------------
          0 |      8,736       87.36       87.36
          1 |        483        4.83       92.19
          2 |         30        0.30       92.49
          4 |          1        0.01       92.50
          9 |         83        0.83       93.33
          . |        667        6.67      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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