This excerpt taken from the LLY 10-K filed Feb 22, 2010.
This graph compares the return on Lilly stock with that of the Standard & Poors 500 Stock Index and our peer group for the years 2005 through 2009. The graph assumes that, on December 31, 2004, a person invested $100 each in Lilly stock, the S&P 500 Stock Index, and the peer groups common stock. The graph measures total shareholder return, which takes into account both stock price and dividends. It assumes that dividends paid by a company are reinvested in that companys stock.