The group produces 40 % of the world's oil, but unrest and revolution in member countries has compromised output. (cnbc.com)
This leaves the organization reliant mainly on the numbers submitted by member countries, he says, and «the countries have the bad habit to report only the data they see». (scientificamerican.com)
«There can be different speeds for member countries to adopt come to ever closer union,» she said. (theguardian.com)