The national average cost of on-highway diesel has fallen once again over the past week, posting its fifth uninterrupted drop and hitting its lowest level since late December of 2009, according to new U.S. Energy Department figures.

The 3 cents decline from last week puts it a $3.754 per gallon, for a combined drop of 19 cents over the past five weeks. Compared to the same time a year ago the current price is $1.198 less.

Prices declined in all the different sections of the country over the past week, ranging from a 0.4 cent in the West Coast region, where it averages $2.914, to as much as 4.2 cents in the Central Atlantic states for an average of $3.08, also the highest priced part of the country.

The least expensive price is in the Gulf Coast region at $2.62, down 2.3 cents from last week.

As for regular grade gasoline, it posted a much smaller overall decline of 0.5 cent from last week for a national average of $2.408. While this marks its third consecutive weekly drop, gasoline is up more than 35 cents since hitting a multi-year low $2.044 in January. Compared to the same time a year ago the current average cost is still $1.243 less.

Prices increased less than a penny over the past week in the East Coast and Gulf Coast regions but it gained more than 3 cents in the Rocky Mountain region. All other regions declined. Gasoline ranges from a low of $2.188 in the Gulf Coast region to a high of $2.922 in the West Coast region.

Meantime, the price of crude oil edged higher on Monday, picking up 27 cents in New York trading before settling at $51.91 per barrel. Despite the slight uptick, it’s down 4 cents from last Tuesday’s opening market price of $51.95, following a volatile trading last week and is still down around 50% from more than $100 per barrel hit last July.