The average price of diesel in the U.S. has dropped below $3 per gallon for the first time in more than four years.

According to data from the U.S. Energy Information Administration, the average on-highway diesel price was down to $2.933 per gallon as of Monday. That’s $0.94 (or 24%) lower than it was at this time last year.

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

The national average for diesel was last below $3 per gallon in September 2010.