South Korea recorded the largest change (-26.1%) followed by Poland (-19.1%), Canada (-17.24%) and Japan (-17.2%). Among G20 countries, China saw a decline of 20.2% during the same period. Shrinking youth populations in most OECD countries and some emerging economies stand in sharp contrast to the growth of those populations in other regions of the world. For example, more than 60% of Africa's population is under the age of 25, and this proportion it is expected to increase to 75% by 2015.