A portfolio manager announces that the average of the returns realized in each of the last 10

Question:

A manager announces that the average of the returns realized in each of the last 10 years is 20% per annum. In what respect is this statement misleading?
Portfolio
A portfolio is a grouping of financial assets such as stocks, bonds, commodities, currencies and cash equivalents, as well as their fund counterparts, including mutual, exchange-traded and closed funds. A portfolio can also consist of non-publicly...