Oil output across OPEC's 14 member countries increased by roughly 336,100 barrels per day in May after Libya, Nigeria, and Iraq increased their production, reports CNBC. The spike comes less than a month after OPEC and other exporters agreed to extend their November deal to cut oil output by 1.8 million bpd to March 2018.

Note: Libya and Nigeria are exempt from the OPEC agreement, as civil conflicts have weighed on their countries' oil supplies. Meanwhile, Iraq, which is OPEC's second-largest producer, had agreed to only produce 4.35 million bpd, but has repeatedly failed to meet its quota and continues to produce more than allotted.

Why it matters: The goal of the OPEC agreement is to help eliminate much of the glut in the oil market that has bogged down the industry for years; however, not all countries have kept their end of the bargain. In May, Saudi Arabia, Angola, Kuwait, and Qatar were the only four countries producing at or below their quotas.