The average oil price in 2016 was $44/barrel, the lowest annual average since 2004. The reason: the world oil market is oversupplied, due  largely to the increase in U.S. oil production from shale beginning about 10 years ago. Also, more U.S. oil production puts a positive dent in the U.S. trade deficit. While lower oil prices are cutting into investment and profitability in the oil industry, U.S. consumers are enjoying the bargain at the pump.