For the next several years, what percentage premium $($over the risk$-$free rate$)$ per year should you expect if you decide to invest into a market portfolio $($for example, if you decide to buy a mutual fund that tracks S&P $500$ index$)?$

$4\%$

$5\%$

$5\mathrm{.}5\%$

$6\mathrm{.}5\%$