OPEC said its oil revenue plunged by $438 billion to a 10-year low last year, as an increase in export volumes failed to compensate for the collapse in prices.

The Organization of Petroleum Exporting Countries earned $518.2 billion in 2015 from the sale of crude and refined fuels, the lowest figure since 2005, the group’s Vienna-based secretariat said in its Annual Statistical Bulletin. It boosted exports by 1.7 percent to 23.6 million barrels a day, maintaining its share of global markets, as Iraq increased output and Saudi Arabia pressed on with a policy to squeeze rivals.

Oil futures tumbled by 35 percent last year as U.S. crude production held up despite the Saudi-led strategy to pressure OPEC’s competitors with lower prices. Crude has since recovered, rising almost 90 percent in London from the lows reached in January, as U.S. output retreats and disruptions from Canada to Nigeria help whittle away a global surplus.