Frequencies for sp_limit variable in accident dataset :

SPEED LIMIT |      Freq.     Percent        Cum.
------------+-----------------------------------
         15 |          4        0.86        0.86
         20 |          1        0.22        1.08
         25 |         61       13.17       14.25
         30 |          7        1.51       15.77
         35 |        115       24.84       40.60
         40 |         55       11.88       52.48
         45 |        111       23.97       76.46
         50 |         12        2.59       79.05
         55 |         97       20.95      100.00
------------+-----------------------------------
      Total |        463      100.00

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