Based on things I've read and seen (ie. just a hyphothesis), I believe there's a big dip in creativity as artists increase in learning. I think this is one source of the common (but mistaken) idea that education inhibits creativity---because most people and artists stop actively learning about their craft before they reach their creative and expressive potential.
Also, I put in the red graph for anyone who happens to be amazing and never experienced a dip. You are awesome, and you really shouldn't waste time reading my blog. Unless you are part of that elite group of people who are still in the dip but don't realize it (we all know one or two).