With more humans living longer, nations have seen their share of the population that we commonly refer to as elderly increase. In some nations, Japan in particular, the shift has been obvious in just the last two decades.
Taking a longer view, Bloomberg points out that east Asian nations are increasing their elderly populations at a much faster rate than elsewhere. Countries like South Korea, Thailand, and China may not yet have the same share of seniors in their population as Japan does, but they have aged significantly since 1982.
Note that the world average in 2012 of people over age 65 was only about 7.5% of the population, Aging is becoming a problem in many countries.