The percentage change in a value is given by ...
... percent change = (change)/(original value) × 100%
You have an original value of 2200 and a new value that is 2376-2200 = 176 higher. Filling in these numbers gives you
... percent change = 176/2200 × 100%
... percent change = 0.08 × 100% = 8%
The average ridership increased by 8%.