FILE - Iraq's largest oil refinery in the northern town of Baiji, Iraq.
FILE - Iraq's largest oil refinery in the northern town of Baiji, Iraq.

World oil prices plunged the most last year since the 2008 financial crisis.

As markets closed at the end of 2014, the price for both the international benchmark Brent crude drilled in the North Sea and the West Texas Intermediate tapped in the United States had fallen by more than 45 percent for the year.

Almost all of the freefall occurred since June, when prices were above $100 a barrel. By year's end, Brent was trading at $57.33 a barrel and U.S. crude at $53.27.

Analysts attributed the plummeting prices to a glut of oil on the world market, caused by a variety of factors.

The United States and Canada have increased their oil production, aided by fracking technology that allows drilling companies to reach oil deposits deep in shale formations that previously could not be tapped.  U.S. oil production reached nine million barrels a day, the highest level in more than 30 years.

At the same time, economic growth slowed in China, the world's biggest energy consumer, while Japan's economy dropped into a recession and Europe's 18-nation euro currency bloc edged close to a contraction.

But in the U.S., cheaper oil has led to the lowest gasoline prices for motorists in several years, helping accelerate growth in the world's largest economy.

Oil experts say prices could continue to fall in the first quarter of 2015 before rebounding later in the year.