Still, because the current level is far below the level of 2.07 required to prevent population replacement, the result is net decline.

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Singapore's total fertility rate of 1.2, which represents the number of children that would be born to a woman if she were to live to the end of her child-bearing years, has been below the population replacement rate for more than three decades.

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Larry Summers, Barack Obama's main economic adviser, has noted that current annualised vehicle sales of about 9m are well below the 14m necessary for replacement and rising population, while annualised housing starts are about a quarter of the rate needed to support the forming of new households.

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The reason is that widening replacement-level fertility means population growth is slowing down anyway.

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In China and most of the industrialised world, births and deaths are at or below replacement level (though America's population still rises because of immigration).

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Japan's aging population should not have to suffer for lack of joint replacement surgery.

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Japan's aging population should not have to suffer for lack of joint replacement surgery, for example.

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For example, the public school district has rebounded to about 4, 600 students from a pre-Katrina population of about 6, 100, and around 700 of 1, 000 replacement homes have been built at Keesler Air Force Base.

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Changes in the population of bacteria, such as removal of some of the good bacteria or replacement with some bad bacteria, can lead to a variety of health problems, especially inflammation of the bowel, diarrhea and pain.

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The pattern of swift, uninterrupted decline is now taken as the norm: the UN uses it to project a worldwide convergence towards the replacement rate of fertility (2.1, the rate at which a population stabilises in the long term).

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The natural birth rate in the USA has been below natural replacement rate for nearly a generation, and the USA has relied on massive immigration to continue population growth.

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