Iraqi oil production grew at a faster rate than any country apart from the United States, analysis from the U.S. Energy Information Administration found.

"Despite some supply disruptions and security threats, Iraq was the second-leading contributor to global oil supply growth in 2014, behind only the United States," EIA said in a Monday brief.

Several energy companies operating in northern Iraq pulled their staff out of the region last year amid growing threats from the terrorist group calling itself the Islamic State. EIA said that, despite the threat, total crude oil production in Iraq rose nearly 10 percent from 2013 to average almost 3.4 million barrels per day, which represents about 60 percent of the production growth from members of the Organization of Petroleum Exporting Countries last year.

At the height of its campaign, the Islamic State controlled as many as seven oil fields and was said to be generating as much as $2 million per day in oil revenue. Though the terrorist group seized some refinery and production facilities in northern Iraq last year, the oil-rich Kurdish region and southern production facilities were spared from much of the violence.

Analysis from consultant group IHS last year found the Islamic State insurgency wasn't having much of an impact on the overall oil sector in Iraq. EIA said Iraqi oil production dropped in mid-summer, but rebounded from August because of expansions in infrastructure and improved security.

"In December, Iraq's crude oil production reached 3.75 million bpd, the highest amount on record," EIA's analysis found.