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

Speed Limit |      Freq.     Percent        Cum.
------------+-----------------------------------
          5 |          2        0.02        0.02
         10 |          9        0.09        0.11
         15 |         39        0.39        0.50
         20 |         45        0.45        0.95
         25 |        840        8.40        9.35
         30 |        466        4.66       14.01
         35 |      1,163       11.63       25.64
         40 |        570        5.70       31.34
         45 |        875        8.75       40.09
         50 |        412        4.12       44.21
         55 |      4,093       40.93       85.14
         99 |      1,486       14.86      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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