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

SPEED LIMIT |      Freq.     Percent        Cum.
------------+-----------------------------------
          0 |         24        0.24        0.24
          5 |          2        0.02        0.26
         10 |          3        0.03        0.29
         15 |         24        0.24        0.53
         20 |         21        0.21        0.74
         25 |        565        5.65        6.39
         30 |        433        4.33       10.72
         35 |      1,162       11.62       22.34
         40 |        880        8.80       31.14
         45 |      1,661       16.61       47.75
         50 |        459        4.59       52.34
         55 |      2,263       22.63       74.97
         60 |        181        1.81       76.78
         65 |      1,283       12.83       89.61
         70 |        618        6.18       95.79
         75 |        179        1.79       97.58
         80 |          1        0.01       97.59
         90 |          2        0.02       97.61
         99 |        239        2.39      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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