Exchange Flow Balance graph shows the combined values of tokens moving in and out of exchange wallets over time.
If the value is positive on a certain date, more of a particular token entered the exchanges than left, and vice versa.
As an example, this is ENJ’s Exchange Flow graph for the past 90 days:
Note: keep in mind that this graph shows the combined values of coins moving and exiting exchange wallets. This could mean, theoretically, that if a large number of coins left Exchange A and entered Exchange B, that movement would not be represented on this particular graph as the two transactions would cancel each other out.