The analysis of major cations and anions in a water sample collected from a city's water supply is given below. Ions present in minor concentrations are not given.
\[
\begin{array}{|l|c|c|c|c|}
\hline
\text{Anions} & \mathrm{Cl}^{-} & \mathrm{SO}_{4}^{2-} & \mathrm{HCO}_{3}^{-} & \mathrm{CO}_{3}^{2-} \\
\hline
\text{Concentration (mM)} & 1.5 & 0.5 & 1.0 & 0.01 \\
\hline
\text{Cations} & \mathrm{Na}^{+} & \mathrm{Ca}^{2+} & \mathrm{Mg}^{2+} & \mathrm{K}^{+} \\
\hline
\text{Concentration (mM)} & 2 & 0.5 & 0.25 & 0.02 \\
\hline
\end{array}
\]
\[
\begin{array}{ll}
\mathrm{HCl} \rightleftharpoons \mathrm{H}^{+}+\mathrm{Cl}^{-} & pK=-3 \\
\mathrm{H}_{2}\mathrm{SO}_{4} \rightleftharpoons 2\mathrm{H}^{+}+\mathrm{SO}_{4}^{2-} & pK=-3 \\
\mathrm{H}_{2}\mathrm{CO}_{3} \rightleftharpoons \mathrm{H}^{+}+\mathrm{HCO}_{3}^{-} & pK=6.3 \\
\mathrm{HCO}_{3}^{-} \rightleftharpoons \mathrm{H}^{+}+\mathrm{CO}_{3}^{2-} & pK=10.3 \\
\mathrm{HOCl} \rightleftharpoons \mathrm{H}^{+}+\mathrm{OCl}^{-} & pK=7.5
\end{array}
\]
$\text{HOCl}$ (in $\%$) present in the total free chlorine in the water is $\_\_\_\_$ (rounded off to the nearest integer).
