OPEC is the the Organisation of the Petroleum Exporting Countries was set up in 1960. It has 12 member countries that are known as a cartel when it comes to oil production. These countries are:-
Algeria, Angola, Ecuador, Iran, Iraq, Kuwait, Libya, Nigeria, Qatar, Saudi Arabia, United Arab Emirates & Venezuela
The daily oil production in barrels per day:-
Algeria 1,667,000
Angola 1,784,000
Ecuador 505,000
Iran 3,680,000
Iraq 3,115,000
Kuwait 3,127,000
Libya 1,509,000
Nigeria 2,417,000
Qatar 1,966,000
Saudi Arabia 11,530,000
UAE 3,380,000
Venezuela 2,725,000
This totals: 37,405,000 barrels per day from OPEC
Now global total oil production is 91,331,000 barrels per day
Thus:-
37,405,000 / 91,331,000 = 40%
OPEC accounts for just over 40% of Global Oil Production. This really is Big Oil.