This is shown by Upplands lokaltrafik's own statistics, which SVT Nyheter Uppsala has read.
Line three accounts for one-fifth of all times the drivers detected and pressed the unpaid button.
In total, there are just over 24,000 keystrokes during the period October last year until May this year.
Line 3 has so far been at the top every month since the measurements were introduced.
The lines that are extra affected
SVT sat on line 3 towards Gottsunda center and talked planking with the travelers.
See more in the clip above.
Other lines with relatively many keystrokes are line 5, 7, 4 and line 1.