Frequencies for first 10,000 rows of seat_pos variable in person dataset :

    seating |
   position |      Freq.     Percent        Cum.
------------+-----------------------------------
          0 |        937        9.37        9.37
         11 |      5,756       57.56       66.93
         12 |         44        0.44       67.37
         13 |      1,602       16.02       83.39
         18 |          2        0.02       83.41
         19 |          3        0.03       83.44
         21 |        495        4.95       88.39
         22 |        187        1.87       90.26
         23 |        511        5.11       95.37
         28 |         14        0.14       95.51
         29 |         21        0.21       95.72
         31 |         35        0.35       96.07
         32 |         26        0.26       96.33
         33 |         31        0.31       96.64
         38 |          4        0.04       96.68
         39 |         12        0.12       96.80
         42 |          1        0.01       96.81
         50 |         20        0.20       97.01
         51 |        109        1.09       98.10
         52 |         22        0.22       98.32
         54 |          1        0.01       98.33
         55 |         11        0.11       98.44
         98 |         27        0.27       98.71
         99 |        129        1.29      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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