In our current side we have Wilshere, Gibbs, Szczesny all from the academy and over the past 10 years we've had a steady flow of decent midtable quality players who've we've sold on for a decent amount too. Bit further back we had Ashley Cole and Clichy as well. That's superior to Utd, Liverpool, Chelsea, City and Spurs.
Thats not to say that we cant do better of course. End of the day, if you can get a Cole or a Wilshere through every 5 years then you're doing well.