Frequencies for phour variable in parkwork dataset :

 crash time |
     (hour) |      Freq.     Percent        Cum.
------------+-----------------------------------
          0 |         66        5.83        5.83
          1 |        105        9.27       15.09
          2 |         99        8.74       23.83
          3 |         69        6.09       29.92
          4 |         22        1.94       31.86
          5 |         18        1.59       33.45
          6 |         38        3.35       36.80
          7 |         29        2.56       39.36
          8 |         19        1.68       41.04
          9 |         36        3.18       44.22
         10 |         28        2.47       46.69
         11 |         37        3.27       49.96
         12 |         35        3.09       53.05
         13 |         54        4.77       57.81
         14 |         43        3.80       61.61
         15 |         56        4.94       66.55
         16 |         60        5.30       71.84
         17 |         39        3.44       75.29
         18 |         45        3.97       79.26
         19 |         28        2.47       81.73
         20 |         49        4.32       86.05
         21 |         68        6.00       92.06
         22 |         44        3.88       95.94
         23 |         44        3.88       99.82
         99 |          2        0.18      100.00
------------+-----------------------------------
      Total |      1,133      100.00

by Jean Roth , jroth@nber.org , 22 Oct 2016