If most of the population arrives at age 20, it would almost totally cut out infant mortality. As the article points out on the first page, infant mortality ha

If most of the population arrives at age 20, it would almost totally cut out infant mortality. As the article points out on the first page, infant mortality has the greatest effect on their longevity numbers: "By the same logic, one infant’s dying during childbirth -- 77.8 years too early -- is equal to ten people’s succumbing to lung cancer at age 70." However, the article is not only about how much healthier New York is relative to the rest of the country -- it's also about how much healthier it is relative to itself about ten years ago. One has to wonder if the immigration rate of 20-year-olds has increased that much in that time.