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

 Crash Time |
     (HOUR) |      Freq.     Percent        Cum.
------------+-----------------------------------
          0 |        364        3.64        3.64
          1 |        314        3.14        6.78
          2 |        395        3.95       10.73
          3 |        244        2.44       13.17
          4 |        237        2.37       15.54
          5 |        306        3.06       18.60
          6 |        330        3.30       21.90
          7 |        347        3.47       25.37
          8 |        270        2.70       28.07
          9 |        312        3.12       31.19
         10 |        327        3.27       34.46
         11 |        383        3.83       38.29
         12 |        421        4.21       42.50
         13 |        415        4.15       46.65
         14 |        430        4.30       50.95
         15 |        463        4.63       55.58
         16 |        566        5.66       61.24
         17 |        592        5.92       67.16
         18 |        604        6.04       73.20
         19 |        568        5.68       78.88
         20 |        594        5.94       84.82
         21 |        585        5.85       90.67
         22 |        397        3.97       94.64
         23 |        399        3.99       98.63
         99 |        137        1.37      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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