The operative word here is "average." That means that the prices were higher and lower in differing states.
You bet.
Gasoline was $1.65 in 2007, went up to $3.85, and is now back down to $2.35,
According to the link I posted, more than $2.50, nationwide in 2007, about $2.35, nationwide, now.
A net drop, not a 40% increase.