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

Speed Limit |      Freq.     Percent        Cum.
------------+-----------------------------------
          0 |         46        0.46        0.46
         10 |          4        0.04        0.50
         15 |         19        0.19        0.69
         20 |         41        0.41        1.10
         25 |        767        7.67        8.77
         30 |        582        5.82       14.59
         35 |      1,318       13.18       27.77
         40 |        852        8.52       36.29
         45 |      1,088       10.88       47.17
         50 |        420        4.20       51.37
         55 |      4,405       44.05       95.42
         60 |          2        0.02       95.44
         65 |        297        2.97       98.41
         99 |        159        1.59      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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