The bar graph below has been seen many times across the online world of finance since its release. It comes from Jeremy Grantham's GMO, and it is their forecast of how asset classes will perform over the next 7 years. The graph is so widely followed because of GMO's track record in correctly predicting future gains and losses.
The following shows GMO's previous forecasts vs. their actual outcome. You are unlikely to find another source in the market place anywhere near to this precision.
Here is their current forecast, which provides a follow up to my discussion earlier in the week on U.S. vs. emerging stock market valuations. GMO believes that emerging market stocks will provide an average return of 6.9% while U.S. stocks will lose an average of 1.1% (3 green bars averaged). Click for larger image: