By 2020, the number of super-aged societies, or those with more than 20 percent of the population aged 65 or over, will more than quadruple to 13 and by 2030, that number will surge to 34, compared with just three countries currently, Moody's said.
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"All countries, except a handful in Africa, will face either a slower-growing or declining working-age population, and corresponding pressures on labor supply" through 2030, it said, noting 16 countries will see their working-age population fall by more than 10 percent over the period. "Population aging will also reduce household savings rates, which will reduce investment."
It cited Conference Board data indicating aging will slow aggregate annual growth rates by 0.4 percentage point in 2014-19 and 0.9 percentage point during 2020-25, shaving the 2.9 percent average annual growth rate over 1990-2005.
It's not just a developed markets problem, with many emerging markets aging even more rapidly than their developed peers.
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China's working age population is expected to fall by 2.7 percent over 2015-30, while countries as diverse as Cuba, Russia, Hong Kong and Croatia are expected to see their working-age population fall by more than 10 percent over the same period, Moody's said.
The aging population is "Asia's foremost long-term headwind," HSBC said in a note Thursday.