Which countries excel at the younger age groups?

Found some interesting stats on which European nations are performing best at U17, U19 and U21 level. It's particularly interesting to see what percentage of these players actually progress through each level and end up with the senior team.

http://www.thestatszone.com/articles/young-players-international--senior-caps-europe

Obviously some of the smaller nations have higher percentages purely because of having a smaller pool of player to choose from.

What particularly interested me is the stark contrast between the England and Germany U21 teams from the 2009 European Championships final - the vast majority of that German unit are still together now, whereas I couldn't tell you who some of those England players are!