The early transactions were at a much lower conversion rate so they would be of larger BTC that tended to raise the average $/txn. But if Bitcoin as a payment network were growing exponentially, we would expect a large proportion of transactions to be relatively recent and at recent valuations.

So either: A. Bitcoin is used for transactions of over $1000 on average, or B. speculation is driving up the valuation far beyond its utility.

In either case, it's clearly not about frictionless microtransactions anymore.