1/3 to 2/3 of arbitrage profit may not be distributed
Arbitrage profit is always divided by 3, despite some indicies might have an INVALID_POOL_ID. That means if an index has an invalid pool id, that 33% of arbitrage profits will not be distributed.
PoolStats.sol#L111-L126
Count the number of indicies without an INVALID_POOL_ID, and then distribute the profit evenly among them
