Shares have delivered impressive long-term returns. The US is the biggest market in the world, and its long history lends itself well to analysis. Between 1900 and today, US shares have returned 9.8 per cent per annum (including dividends). That means an investor has, on average, doubled their money every 7.4 years. Not bad at all. That’s a recipe for wealth generation, and an excellent way to ensure your capital grows more than inflation (which has been three per cent per annum over that entire period) and your purchasing power is maintained. However, what’s equally interesting is to consider the typical return in any given calendar year. I did that, and the results surprised me.