In the following video, Motley Fool financial analysts Matt Koppenheffer and David Hanson discuss Warren Buffett's letter to Berkshire Hathaway (NYSE:BRK-B) shareholders this year. In the letter, Buffett tells shareholders that it was a "sub-par" year, and one of only nine years in the company's 48-year history that it has grown in book value less than the S&P 500's percentage gain for the year. Matt puts this "disappointment" into perspective by looking at Berkshire's performance on a longer timeline.