New Delhi, Sept. 18 -- AN UNFORTUNATE CLUB of countries is gaining new members. China, the world's second-biggest economic power, and Russia, the most belligerent one, have joined. So have Germany, a far richer big economy, and Brazil, which may soon export more farm products than America. Some 3.3bn people, or more than two in five humans, now live in places where GDP per person grew half as fast or less in the decade to 2024 than in the previous ten years. In 2014 the figure was 1.1bn, or fewer than one in six people. Over 730m are experiencing outright declines in economists' favourite gauge of living standards.

Some places continue to grow richer. The average resident of these lucky locales saw their real income grow by 38% between 2...