Determination of Young's Modulus Using Searle's Method

To determine the spring constant of a spring following graph is plotted. The graph shows the variation of mass $m$ in pan versus the extension $\left(e\right)$.

In the Searle's experiment after every loading a gap of short interval is given to ensure that

In an experiment a wire of diameter $5.0 \mathrm{mm}$ is stretched by a force of $200 \mathrm{kg}$ weight. $\mathrm{Y}=\left(12.5 \times {10}^{11}\right) \mathrm{dyne} {\mathrm{m}}^{-2}$. The percentage increase in its length is