Frequencies for phour variable in parkwork dataset :

 crash time |
     (hour) |      Freq.     Percent        Cum.
------------+-----------------------------------
          0 |         52        4.54        4.54
          1 |         61        5.32        9.86
          2 |         83        7.24       17.10
          3 |         37        3.23       20.33
          4 |         29        2.53       22.86
          5 |         24        2.09       24.96
          6 |         39        3.40       28.36
          7 |         40        3.49       31.85
          8 |         45        3.93       35.78
          9 |         43        3.75       39.53
         10 |         35        3.05       42.58
         11 |         48        4.19       46.77
         12 |         42        3.66       50.44
         13 |         38        3.32       53.75
         14 |         61        5.32       59.08
         15 |         53        4.62       63.70
         16 |         57        4.97       68.67
         17 |         36        3.14       71.82
         18 |         40        3.49       75.31
         19 |         56        4.89       80.19
         20 |         55        4.80       84.99
         21 |         41        3.58       88.57
         22 |         62        5.41       93.98
         23 |         66        5.76       99.74
         99 |          3        0.26      100.00
------------+-----------------------------------
      Total |      1,146      100.00

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