How an ageing population will change the world The number of people across the world over 65 years old will triple by 2050, drastically altering some countries' demographic make-up, according to a new report by the Pew Research Center. Perceptions of this shift vary widely across the globe, the report says. While 87% of Japanese believe the ageing population poses a problem to the country, only 26% of Americans agree. The survey of 21 countries found that most people believe governments should be responsible for the care of their older populations. These demographic shifts may adversely affect economies, as more elderly people depend on working-age men and women. Produced by the BBC's David Botti