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

    roadway |
      grade |      Freq.     Percent        Cum.
------------+-----------------------------------
          0 |         63        0.63        0.63
          1 |      6,846       68.46       69.09
          2 |        256        2.56       71.65
          3 |        104        1.04       72.69
          4 |         24        0.24       72.93
          5 |        672        6.72       79.65
          6 |        850        8.50       88.15
          8 |      1,123       11.23       99.38
          9 |         62        0.62      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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