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

SPEED LIMIT |      Freq.     Percent        Cum.
------------+-----------------------------------
          0 |         46        0.46        0.46
         10 |          3        0.03        0.49
         15 |         22        0.22        0.71
         20 |         30        0.30        1.01
         25 |        598        5.98        6.99
         30 |        587        5.87       12.86
         35 |      1,334       13.34       26.20
         40 |        817        8.17       34.37
         45 |      1,373       13.73       48.10
         50 |        462        4.62       52.72
         55 |      3,992       39.92       92.64
         60 |          1        0.01       92.65
         65 |        615        6.15       98.80
         99 |        120        1.20      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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