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

Speed Limit |      Freq.     Percent        Cum.
------------+-----------------------------------
          5 |          1        0.01        0.01
         10 |          3        0.03        0.04
         15 |         21        0.21        0.25
         20 |         30        0.30        0.55
         25 |        891        8.91        9.46
         30 |        462        4.62       14.08
         35 |      1,342       13.42       27.50
         40 |        647        6.47       33.97
         45 |        902        9.02       42.99
         50 |        414        4.14       47.13
         55 |      4,076       40.76       87.89
         99 |      1,211       12.11      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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