How OPEC Won the Battle and Lost the War

OPEC's members now fight each other, and the likes of the U.S., for market share.
This Herfindahl-Hirschman Index shows competition, based on each country's share of output. A score of 2,500 or more indicates a highly-concentrated market; below 1,500 shows healthy competition.
Conditions were perfect for OPEC 40 years ago. But this is one `70s revival that isn't happening.