The reason for this is improving health care, allowing people to live longer, coupled with a declining birth rate.

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Scientists have cloned sheep, cows, goats, pigs and mice, but their success rate is as low as one live birth in 100 attempts.

CNN: Group says it will move human cloning work offshore

" This tells you how often a clinic was able to achieve a live birth, or in layman's terms, the clinic's "success rate.

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