A thermally insulated vessel contains some water at $0^{0}C$ . The vessel is connected to a vacuum pump to pump out water vapour. This results in some water getting frozen. It is given Latent heat of vaporization of water at $0^{0}C=21\times {10}^{5}J/kg$  and latent heat of freezing of water $=3.36\times {10}^{5}J/kg$ . The maximum percentage amount of water that will be solidified in this manner will be