Frequencies for phour variable in parkwork dataset :

 crash time |
     (hour) |      Freq.     Percent        Cum.
------------+-----------------------------------
          0 |         54        4.96        4.96
          1 |         48        4.41        9.37
          2 |         67        6.15       15.52
          3 |         31        2.85       18.37
          4 |         37        3.40       21.76
          5 |         30        2.75       24.52
          6 |         27        2.48       27.00
          7 |         34        3.12       30.12
          8 |         43        3.95       34.07
          9 |         33        3.03       37.10
         10 |         29        2.66       39.76
         11 |         45        4.13       43.89
         12 |         52        4.78       48.67
         13 |         46        4.22       52.89
         14 |         44        4.04       56.93
         15 |         58        5.33       62.26
         16 |         48        4.41       66.67
         17 |         62        5.69       72.36
         18 |         55        5.05       77.41
         19 |         35        3.21       80.62
         20 |         55        5.05       85.67
         21 |         57        5.23       90.91
         22 |         47        4.32       95.22
         23 |         51        4.68       99.91
         99 |          1        0.09      100.00
------------+-----------------------------------
      Total |      1,089      100.00

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