The Energy Information Administration, the department's analytic arm, said the Organization of the Petroleum Exporting Countries for all members except Iran earned nearly $982 billion in net oil export revenues last year. That's a 5 percent increase from 2011.
Saudi Arabia accounted for 32 percent of the total OPEC revenues in 2012 with $311 billion, the EIA said. OPEC said in its July market report that Saudi Arabia produced 9.7 million barrels of oil per day last year, a 4.3 percent increase from 2011.
OPEC said Iran in 2012 was the second-largest oil producing state among its members with 3.7 million bpd. EIA said Monday it excluded Iran because of difficulties associated with assessing Iran's economy, "including its inability to receive payments and possible price discounts Iran offers its existing customers."
Sanctions imposed on Iran make it difficult for the country to capitalize on its oil and natural gas reserves.
Demand for OPEC crude has declined because of production gains from North America. The EIA, however, said it estimates OPEC members, excluding Iran, could make $940 billion of net oil export revenues this year.