This basic metric is calculated by dividing the average daily gas spend by the quantity of transactions. The logic being that a basic transaction on Ethereum has a 21,000 gas limit while more complex smart contracts (ie ICOs, crypto[insert animal], token transfers, airdrops, spam drops, staking payouts etc) require a higher limit. (*Note: this metric uses the assumed gas cost calculation of: IF ETH = $1000, THEN 21000 gas will cost 0.00000002 * 1000 * 21000 = 0.42 dollars, which is $0.42 cents USD).