The average on-highway diesel price in the U.S. was down to $3.801 per gallon as of Monday, according to data from the U.S. Energy Information Administration.

A year ago, the average diesel price was $3.974 per gallon, so the current average is $0.173 (or 4.4%) lower.

The average diesel price in the U.S. has been on a slow decline since March 10 of this year, when it peaked at $4.021 per gallon.

The latest average of $3.801 per gallon for diesel is the lowest since July 30, 2012, when the average was $3.796.