The plot given below shows $\mathrm{P}-\mathrm{T}$ curves (where, $\mathrm{P}$ is the pressure and $\mathrm{T}$ is the temperature) for two solvents $\mathrm{X}$ and $\mathrm{Y}$ and isomolal solutions of $\mathrm{NaCl}$ in these solvents. $\mathrm{NaCl}$ completely dissociates in both the solvents.



On the addition of equal number of moles of a non-volatile solute $\mathrm{S}$ in equal amount (in $\mathrm{kg}$) of these solvents, the elevation of boiling point of solvent $\mathrm{X}$ is three times that of solvent $\mathrm{Y}$. The solute $\mathrm{S}$ is known to undergo dimerization in these solvents. If the degree of dimerization is $0.7$ in the solvent $\mathrm{Y}$, the degree of dimerization in the solvent $\mathrm{X}$ is _______.