Frequencies for not_hour variable in accident dataset :

Notificatio |
     n Time |
   EMS-Hour |      Freq.     Percent        Cum.
------------+-----------------------------------
          0 |        496       86.87       86.87
         99 |         75       13.13      100.00
------------+-----------------------------------
      Total |        571      100.00

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