Frequencies for first 10,000 rows of hour variable in accident dataset :

 Crash Time |
     (Hour) |      Freq.     Percent        Cum.
------------+-----------------------------------
          0 |        407        4.07        4.07
          1 |        391        3.91        7.98
          2 |        429        4.29       12.27
          3 |        315        3.15       15.42
          4 |        249        2.49       17.91
          5 |        284        2.84       20.75
          6 |        380        3.80       24.55
          7 |        306        3.06       27.61
          8 |        291        2.91       30.52
          9 |        309        3.09       33.61
         10 |        319        3.19       36.80
         11 |        351        3.51       40.31
         12 |        430        4.30       44.61
         13 |        372        3.72       48.33
         14 |        493        4.93       53.26
         15 |        467        4.67       57.93
         16 |        517        5.17       63.10
         17 |        539        5.39       68.49
         18 |        539        5.39       73.88
         19 |        547        5.47       79.35
         20 |        572        5.72       85.07
         21 |        510        5.10       90.17
         22 |        471        4.71       94.88
         23 |        411        4.11       98.99
         99 |        101        1.01      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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