Frequencies for last_mo variable in vehnit dataset :

       LAST |
ACCIDENT-MO |
        NTH |      Freq.     Percent        Cum.
------------+-----------------------------------
          . |      1,116      100.00      100.00
------------+-----------------------------------
      Total |      1,116      100.00

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