A lead ball of specific heat $125\mathrm{Jk}{{\mathrm{g}}^{-1}}^0{\mathrm{C}}^{-1}$ at ${20}^{0}C$ is dropped from a height of 2km. It is subjected to air resistance, and it is assumed that all of its kinetic energy is used in increasing the temperature of  ball. Final temperature of the ball in ${ }^{0}C$ is _________ times initial temperature of ball in ${ }^{0}C$.