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

SPEED LIMIT |      Freq.     Percent        Cum.
------------+-----------------------------------
          0 |         39        0.39        0.39
          5 |          5        0.05        0.44
         10 |          7        0.07        0.51
         15 |         28        0.28        0.79
         20 |         32        0.32        1.11
         25 |        555        5.55        6.66
         30 |        483        4.83       11.49
         35 |      1,203       12.03       23.52
         40 |        827        8.27       31.79
         45 |      1,756       17.56       49.35
         50 |        470        4.70       54.05
         55 |      2,444       24.44       78.49
         60 |        171        1.71       80.20
         65 |      1,168       11.68       91.88
         70 |        498        4.98       96.86
         75 |        147        1.47       98.33
         99 |        167        1.67      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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