In an arc welding process, the voltage and current are $30 \mathrm{~V}$ and $200 \mathrm{~A}$, respectively. The cross-sectional area of the joint is $20 \mathrm{~mm}^{2}$ and the welding speed is $5 \mathrm{~mm} / \mathrm{s}$. The heat required to melt the material is $20 \mathrm{~J} / \mathrm{s}$. The percentage of heat lost to the surrounding during the welding process is _________ (rounded off to $2$ decimal places).
