Frequencies for first 10,000 rows of a_vroll variable in veh_aux dataset :

   Rollover |      Freq.     Percent        Cum.
------------+-----------------------------------
          1 |      1,967       19.67       19.67
          2 |      8,033       80.33      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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