The average life expectancy in Japan has extended 4.2 years over the past 25 years as of 2015, while the gap between prefectures has widened during the same period, researchers have found.

A research team, led by Kenji Shibuya, a University of Tokyo professor of health policy, found that average life expectancy has increased to 83.2 years from 79.0 years during the quarter-century period.

They also discovered that the healthy life expectancy has also improved to 73.9 years as of 2015, from 70.4 years in 1990.