Oil markets slid to new lows Friday after the International Energy Agency lowered its forecast for demand growth in 2015, the latest sign that the market could remain oversupplied well into next year.

Concerns about a global oil glut have sent prices plunging more than 45% since mid-June, and the selloff has accelerated since the Organization of the Petroleum Exporting Countries decided last month to maintain its production quota.

Falling oil prices are expected to boost economic growth, especially in large consuming nations, but they could threaten the economic health of oil producers and lead to lower investment in expensive drilling projects.

The national average price of retail gasoline in the U.S. fell to $2.60 a gallon Friday, the lowest average since December 2009, according to AAA. The auto club expects prices to fall to $2.50 a gallon before Christmas.

On Friday, the Paris-based IEA cut its forecast for 2015 oil demand growth by 230,000 barrels a day to 900,000 barrels a day. The energy watchdog has cut its demand-growth forecast five times in the last six months.

“We’ve had a plunge in prices…and the IEA is still lowering the demand forecast,” said Stephen Schork, editor of industry newsletter The Schork Report. For prices, “no one can tell you where the floor is right now.”

Light, sweet crude for January delivery fell $2.14, or 3.6%, to $57.81 a barrel on the New York Mercantile Exchange, the lowest settlement price since May 15, 2009. Prices slid 12.2% this week and are down 41% year-to-date.

Brent, the global benchmark, fell $1.83, or 2.9%, to $61.85 a barrel on ICE Futures Europe, the lowest level since July 14, 2009. Prices are down 10.5% on the week and 44% on the year.

OPEC and the U.S. Energy Information Administration also lowered their demand forecasts for 2015 this week.

“The market really has nothing going for it right now–there’s nothing encouraging,” said Andy Lebow, senior vice president for energy at Jefferies LLC. “There’s no prospect of near-term production cuts.”

The drop in oil prices has also hammered energy stocks and weakened the currencies of oil-producing nations, forcing some central banks to respond.

January reformulated gasoline blendstock, or RBOB, settled down 2.71 cents, or 1.7%, at $1.5973 a gallon, the lowest settlement since May 5, 2009. Prices posted a 9.9% loss on the week.

January diesel slid 4.54 cents, or 2.2%, to $2.0160 a gallon, the lowest price since August 2010. Prices fell 4.4% this week.