The elementary second-order liquid phase reaction $A+B{\rightarrow}C+D$ is carried out in an isothermal plug flow reactor of $2\:m^{3}$ volume. The inlet volumetric flow rate is $10\:m^{3}/h$. The initial concentration of both $A$ and $B$ are $2\: k$mol/$m^{3}$. The rate constant is given as $2.5\:m^{3}\:k$mol$^{-1}$ $h^{-1}$. The percentage conversion of $A$ is ______________.