shows that the one-year standard deviation of 18.1 percent drops by more than half, to 7.5 percent, over just five years. It is cut nearly in half again, to 4.4 percent, over 10 years. Though most of the sting of volatility has been eliminated after a decade, it continues to decline as the period lengthens, until it reaches just 1.0 percent over an investment lifetime of 50 years, with an upper range of return of 7.7 percent and a lower range of 5.7 percent.
