Abstract Painting (809-4) Gives Clapton 21% Annualized Return

There was an article in the Journal today about a painting by Gerhard Richter entitled Abstract Painting (809-4) which sold for $34m, the highest price ever for a living artist's work.  The article mentions that the painting was purchased by Eric Clapton for $3.1m in 2001, which is a 21.2% annualized return.  For comparison, AAPL has given a ~41% annualized return and Gold has returned ~16% per year since then.  The S&P has returned about 1.5% before dividends in the same time.