Frequencies for first 10,000 rows of underide variable in vehicle dataset :

underride/o |
    verride |      Freq.     Percent        Cum.
------------+-----------------------------------
          0 |      9,902       99.02       99.02
          1 |         32        0.32       99.34
          2 |          5        0.05       99.39
          3 |         19        0.19       99.58
          4 |          3        0.03       99.61
          5 |          2        0.02       99.63
          6 |          3        0.03       99.66
          7 |         25        0.25       99.91
          8 |          2        0.02       99.93
          9 |          7        0.07      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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