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 |          4        0.04        0.06
         15 |         25        0.25        0.31
         20 |         20        0.20        0.51
         25 |        938        9.38        9.89
         30 |        446        4.46       14.35
         35 |      1,313       13.13       27.48
         40 |        692        6.92       34.40
         45 |        853        8.53       42.93
         50 |        415        4.15       47.08
         55 |      4,084       40.84       87.92
         99 |      1,208       12.08      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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