Long term portfolio returns

The returns of different asset classes after inflation from 1926 to 2000 reveal the long-term average returns. In the long run, small stocks have returned on average 13.8% and large stocks 9.7%. The volatility for small stocks has been very high with a 32.8% standard deviation (a measurement of volatility), which is not necessarily desirable for the average portfolio. Large stocks on the other hand have the risk/return parameters an average investor expects. Bonds have provided less than 3.0% on average, which proves the benefit of stock investing in creating wealth.

Source: Ibbotson Associates

It is clear why stocks are considered the best way to build wealth.