New York times has an interesting infographic showing stock market (S&P 500) returns over long time periods. The article stresses when you put money in and take it out it is of great importance. Staying invested in markets for extended periods of time without paying attention to the buying valuation is not a recipe for success. For example, 1961-1981, a 20 year period yielded -2.1% per annum.
Value investors are well aware of this fact and also know that this has to do with valuation (e.g. P/E ratios), which the article unfortunately neglects to mention.
