you observe the following current Treasury yields:

$1$R$1=2\mathrm{.}52\%$; $1$R$2=2\mathrm{.}75\%$; $1$R$3=3\mathrm{.}31\%$; $1$R$4=4\mathrm{.}08\%$; $1$R$5=4\mathrm{.}77\%$

If the unbiased expectations theory holds, what is the one$-$year rate expected during year $4?$