The conductivity of water at 298 K is $5.54\times {10}^{-8}\mathrm{S}{\mathrm{cm}}^{-1}$. If ${\lambda }_{{\mathrm{H}}^{+}}^{\mathrm{\infty }}=349.8\mathrm{S}{\mathrm{cm}}^2{\mathrm{mol}}^{-1}$ and ${\lambda }_{{\mathrm{OH}}^{-}}^{\mathrm{\infty }}=197.8\mathrm{S}{\mathrm{cm}}^2$ ${\mathrm{mol}}^{-1}$, the degree of dissociation of water is