The congestion charge does seem to be effective, as 2-person cars are the highest on the table of cars entering the city. Also, the mean has increased to 2.37, people per car on average (farther away from an average of 1 person per car than before), which shows that the congestion charge has worked.
How I found the new mean:
[(1 x 17) + ( 2 x 54) + (3 x 14) + (4 x 8) + (5 x 2)] / (17 + 54 +14 +8 + 2)
mean = sum of values / number of values