Median age in each country of the world.

Charts Bin shows great differences between countries.  Canada, much of Europe and Japan have a median age over 40 and most of Africa has a median age under 20.  "Median" means half the population is older and half the population is younger than this number.  At the link, if you hover over a country, the age by sex will appear too.

How can a country prosper when there are almost no experienced adults around?
How can it prosper when a majority are pensioned off and out of the work force?
The TED lecture by Hans Rosling with animations reveal how rapidly life spans are increasing worldwide.  The best talk I have seen.  The muslim nations will be turning orange soon.