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

    roadway |
      grade |      Freq.     Percent        Cum.
------------+-----------------------------------
          0 |         52        0.52        0.52
          1 |      7,191       71.91       72.43
          2 |        250        2.50       74.93
          3 |        121        1.21       76.14
          4 |         15        0.15       76.29
          5 |        682        6.82       83.11
          6 |        905        9.05       92.16
          8 |        720        7.20       99.36
          9 |         64        0.64      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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