In a fusion reaction, a deuteron and a triton join to form a helium nucleus and a neutron, and release $17.6\ \text{MeV}$. In a reactor, one nucleus of uranium-235 undergoes fission and releases $200\ \text{MeV}$. Take the mass of a deuteron as $1875.6\ \text{MeV}/c^2$, the mass of a triton as $2808.9\ \text{MeV}/c^2$ and the mass of a uranium-235 nucleus as $235\ \text{u}$, with $1\ \text{u} = 931.5\ \text{MeV}/c^2$. By what factor is the fraction of the starting mass that is changed into energy larger in the fusion than in the fission?