Stock mutual funds that focus on investing in Europe are struggling but have kept a performance edge over the S&P 500 and the MSCI EAFE index for the past 15 years. A $10,000 investment in the average Europe fund tracked by Morningstar on Sept. 30, 1999, would have grown to $19,971 by Oct. 17 this year. The same amount would have run up to $19,547 if plunked down on the S&P 500, a prox y for the broad U.S. stock market.