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

SPEED LIMIT |      Freq.     Percent        Cum.
------------+-----------------------------------
          0 |         33        0.33        0.33
          5 |          1        0.01        0.34
         10 |          3        0.03        0.37
         15 |         19        0.19        0.56
         20 |         20        0.20        0.76
         25 |        507        5.07        5.83
         30 |        484        4.84       10.67
         35 |      1,119       11.19       21.86
         40 |        905        9.05       30.91
         45 |      1,606       16.06       46.97
         50 |        450        4.50       51.47
         55 |      2,545       25.45       76.92
         60 |        135        1.35       78.27
         65 |      1,164       11.64       89.91
         70 |        630        6.30       96.21
         75 |        191        1.91       98.12
         99 |        188        1.88      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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