(AP) The price of oil plunged again Monday and briefly dipped below $50 a barrel for the first time in more than five years as evidence mounted that the world will be oversupplied with oil this year. Benchmark U.S. oil dipped to $49.95 before quickly rising back over $50. In early afternoon trading oil was down $2.29, or 4.3 percent, to $50.40 a barrel. In June of last year, it traded above $107 a barrel. Brent crude, a global benchmark used to price oil used by many U.S. refineries, was down $3.05, or 3.4 percent, to $53.37. Oil has been falling for several months because global supplies are rising, especially in the U.S., at a time when weakness in the global economy is slowing the growth in oil demand. On Monday, Citigroup cut its forecast for 2015 global oil prices as a result of high supplies.