By Francesca Colombo. That population is ageing across the world is well known. As fertility rates drop and life expectancy improves, a bigger share of the population is greying. At least one in four people will be aged over 65 by 2050 in about two-thirds of OECD countries. The share of those aged over 80 years will more than double, from 4% in 2010 to 10% in 2050. In Japan, Spain and Germany, this trend will be even more pronounced, with the proportion of the over-80s expected to triple, rising from 5% to 15% in Spain and Germany, and from 6% to 16% in Japan. The speed of ageing will be even more dramatic in some emerging economies. China, for example has taken only 40 years to increase life expectancy from 40 to 70 years, something that took Germany 80 years. More...