Stock market history has a few lessons for investors. One of the most potent is that stocks usually go up. Another is that stocks usually have pullbacks greater than 10% every year. (The average drawdown in the last 40 years is 14.2% intrayear, according to JPMorgan.) And in the relatively rare instances where stocks have seen declines greater than 10% in a calendar year, one of three reasons has been the trigger. Sign up for the Yahoo Finance Morning Brief By subscribing, you are agreeing to Yahoo ...