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

underride/o |
    verride |      Freq.     Percent        Cum.
------------+-----------------------------------
          0 |      9,918       99.18       99.18
          1 |         31        0.31       99.49
          2 |          7        0.07       99.56
          3 |         13        0.13       99.69
          4 |          2        0.02       99.71
          5 |          1        0.01       99.72
          6 |          1        0.01       99.73
          7 |         13        0.13       99.86
          8 |          3        0.03       99.89
          9 |         11        0.11      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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