From sample surveys, officials estimate the population at the end of 2009 to have been 1.33 billion.

ECONOMIST: China's ten-yearly census: The world's biggest headcount | The

Jaime Gahche, main author of the CDC report, and her co-authors analyzed responses from a sample size of 37, 596, using National Health and Nutrition Examination surveys.

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On the basis of the national sample surveys (NSS), they calculate that India's sex ratio at birth swung from 924 females per 1, 000 males in 2004-05 to 977 in 2011, a stunning turnaround in favour of girls.

ECONOMIST: Banyan