Suppose we observe the three$-$year Treasury security rate ${(}_1{R}_3)$ to be $4\mathrm{.}5$ percent, the expected oneyear rate next year$-E(2r_1)-$to be $5\mathrm{.}5$ percent, and the expected one$-$year rate the following yearE${(}_3{r}_1)-$to be $5\mathrm{.}9$ percent. If the unbiased expectations theory of the term structure of interest rates holds, what is the one$-$year Treasury security rate?

Note: Do not round intermediate calculations. Round your percentage answer to $2$ decimal places $($e$.$g$.,32\mathrm{.}16).$